I haven't done exactly this. I've made foil-based transformers in other sizes, and made converters in comparable power levels. (In particular was a 5kW inverter for induction heater service; it ran at 20-400kHz depending on configuration, and used a T107/65/25-3F3 core with Litz for primary and secondary. The Litz cable was easy, no problems...)
Last one I did with foil, was... this:

(don't mind the notes about finding the right gap

), for a little converter,

120-800V DC output, about 50-100W capacity (12V input), dual output flyback topology. (The outputs are wired in series, so that doesn't actually amount to anything in the end; it does make the waveform far cleaner, though -- the secondary is effectively a balanced circuit.)
The windup is in order: 1 turn primary, 15 secondary, 1 pri, 15 sec, 1 pri. Don't have any pics of the transformer under construction, but what I did was, I used copper foil tape for the turns themselves, and made connections by soldering 20AWG bare copper wire onto the ends. Secondary is 28AWG. This took up very little space on the bobbin, only needing ~1kV functional isolation (since the output is common ground). I happen to have a bunch of these core sets, so it's rather oversized, or, the windup is rather disproportionate. It doesn't seem to heat up much under normal load conditions though. Just a simple module for lab use, no big deal.
The obvious downside to this construction, is the thin strip of wire joining together what's otherwise a beastly thick foil turn. Preferably, you'd keep the foil going, by folding it 90° so it goes up and out of the bobbin, so the next section can be wound, and so on.
That would still concentrate current around the foil edges, because you're trying to make a 90 degree turn -- the current has to bunch up somewhere. In this case, it's bunching up under the primary, because of image currents, gathering on the fat outside corner of the bend, and getting carried up the terminal edge and out of the bobbin. But this at least happens only at the ends of the turn, not over its whole length.)
It also doesn't help that, every time you start/end a section with foil turned sideways, the available winding area is reduced by the foil thickness. Preferably, you have a wide winding area. But that implies you need a lot of room to turn the foil through 90°, so the core cross section should be rectangular as well, so the turn can be made on a wide face of the bobbin.
The next-last foil winding I made, I did actually stack two foil layers, but I haven't tested that one yet at full load, so I'm not sure how good its losses are. (That was a necessary step, because the two turns are the ends of a CT winding -- as with your case. Overlapping foil gives low leakage between ends of the CT winding, necessary to minimize snubbing of those switches. Which in your case is the synchronous rectifier; in mine, it's a PP primary, same thing.)
Arguably, this should still be acceptable, as the two halves of the CT winding draw current alternately, so there shouldn't be proximity effect where both turns (on top of each other) are active at the same time -- except only for the currents due to leakage and snubbing (if applicable), which are a small part of the total.
Actually, that may be a much better example; unfortunately, I don't have any photos or drawings handy. Perhaps I can describe it. The windup was thus:
- Start with T87 toroid
- At 90° intervals around the toroid, apply single turns of copper foil tape. Insulate with polyimide tape, leaving the ends of each turn exposed for connection. The connections shall be exposed on one flat face of the toroid. (So, not the inner or outer cylindrical surface, the face between them.)
- Apply single turns of copper foil tape on top of the existing turns. Cut the ends a little bit shorter, so they do not overlap the previous layer's connections.
- Using copper tape, solder and polyimide tape, construct a 90 degree turn, so that the four connections from each pair of turns becomes a 4-layer laminated (flexible) connection, standing up perpendicular from the toroid plane, and aligned radially.
- Wind 24AWG over top the foil windings, and secure with tape.
- Unfold the laminated connections, and connect the foil turns in series-parallel to make a 2+2CT primary winding. Each half of the CT winding is made of the two stacked foil turns in series; two of these are further connected in series to make a 2+2CT primary half. Two of these are connected in parallel to give the full primary winding.
- The primary wiring connections are made in laminated foil and tape construction again; primary leads is made with a 3-layer flexible connection.
This is...probably a nightmare of a description if you have aphantasia.

Ah well...
Anyway, the important part, applicable to your case, is this: to get low leakage between ends of the secondary, you should really use two foil strips stacked (instead of just one), and wrap that around for two turns. Join the end of one with the start of the other, and that's your CT. Except, because this would have about as much current crowding as it is now: instead of making 2+2 turns in a single section, make a single 1+1 turn pair for each section, and use two sections, with primary sections around them (PSPSP if possible, but as you said, you don't have much room to do that; SPS may actually be better here, then?). Then wire the individual turns in series, to construct a 1+1:1+1 CT winding, where the 1's from opposite sides are closely coupled. That is, if we number the turns a, b, c and d, with a+b being one section and c+d being the other, connect them as a+c:b+d.
So the full windup would be:
[a b] [16 turns pri] [c d]
I would also be tempted to suggest a planar transformer. This should be quite reasonable at the low impedance here, but cooling may be a challenge. I've seen designs advertised in this power range before, so it's definitely possible. Downside, lots of NRE and fab time, so if it turns out it sucks anyway, or you end up needing to change the ratio or something...
Tim