I think I have sufficient headroom. 25VDC regulated down to 16VDC.
I'm using MURF860 diodes rated at 8Amps... Vdrop is 1.5V, but that still leaves me with 22VDC, enough headroom for a 16VDC out?
Luckily, I designed the PCB with enough clearance around caps. I'll be able to upgrade to an 18mm dia. cap, and replace my existing 16mm dia. caps with something else. 1500uf to 2200uf apiece comes in 18mm dia package (with same lead spacing).
Here's a photo of PSU I'm working on. I've load tested it for several hours at +/-5Amps, though it will do higher up to 6Amps.