Actually there is another option Dave didn't look at.
The problem is each Solar Generator see's the other's power generation.
Lets say both systems generate the maximum power output, and the house is using minimal/no power.
The Solar Analytics system sees the +3kW from it's connected Solar Generator, but also sees -5kW 'consumption' the other system.
The Enphase Envoy system sees the +5kW from it's connected Solar Generator, but also sees -3kW 'consumption' the other system.
So what is needed is to add the power generated by the other system in both cases.
If you stuff a second wire into each Consumption Current Transformer (CT), that current thru that wire can be added/subtracted from the total.
So run the 3kW wire backwards thru the Consumption CT for the 5kW system.
Run the 5kW wire backwards thru the Consumption CT for the 3kW system.
Reality probably sucks in that you possibly cannot fit a second wire into some of those Current Clamps, or the wires would need to be made longer.
Or just go nuts, and rewire that big fat Active wire so after the main breaker it goes to the Solar system, then back to the loads.