Did some disassembly inside the camper today, to see what type of hidden space is available. Wow. The people who designed and built that unit have never lived in a TC. Move a few items , reroute some wires and lines... I could put a whole new cabinet space in there lol. They used too long sections of hose, so when they pushed it in the space, it kinked. My one impediment to the four GC2s - and I'm really leaning in that direction - is the fresh water tank. One corner protrudes about an inch into the battery space. That's what constricts me to a 14" dimension. If I could scoot the tank back into the basement even a half or quarter inch, then no issue. But I have no access to the basement area where the fresh water tank is banded to the floor. It's only plastic, so maybe it has a quarter inch of give...
Checked out SAMs club today: Duracell EGC2s (230ah) for $109 each. Wet cells. Really want AGMs, though. May reconsider. Might start with the wet cells and see how they work. Easy enough to vent the entire space...
Time to do the hard part and think. Thanks for all the great advice.