I'm switching over from dual 6v's this spring. My battery is already here and will be buying the DC/DC shortly (going with this
Renogy DC/DC 20a). I rarely stay put over 3 days, so last trip (6,800 miles) we took out the solar panel almost by habit vs. requiring. That was charging the LA's from the Tow Vehicle (the LiPo requires different charger). I'm actually reducing my power bank size... My duals are just over 100ah of usable (rated 230ah, then reduce by half and loses).
A 200ah bank of usable amperage would give me 10 days at max consumption.. I've gone to a 60ah LiPo and with conservative cycling, I have 3 days of autonomy.
I've also decided on a smaller solar panel, now carry a 130w and looking at a smaller 80w-100w. Something that packs nicer.
$2500 still sounds like a lot of money ($12.50 per aH).
If you're willing to build your own, there's quite the savings!
These prismatic cells are recommended and worth looking into
LiPo 100aH batteries. Obviously require 4 to reach 100aH @ 12v's. For you 200aH 8 of them @ $124 each $992. Then the BMS of choice, Like this one
Low temp cut-off BMS @ $90. Add the DC/DC charger (even if you wet 40a) another $170. Under $1400 or $6.90 (+-) a aH.