I have the same basic question as Dennis221, so I'll jump in with my answers to ckent323's questions:
Truck: 2009 Tacoma dbl cab, long bed 4wd with (presumably) stock alternator, purchased with camper in 2017.
Camper: 2011 4WD Finch, purchased with truck in 2017, originally sold in Canada (if that makes any difference).
Truck wiring: Appears to be AWG 10 from truck battery to female plug-in for camper in side of bed.Wire diameter with insulation is ca. 3/16".
Camper wiring: Pretty sure wires from 4-wire male plug to separator switch are AWG 10. Not sure about wires from separator switch to battery, thinking they're probably whatever was standard for Finch when 4WD built it. Will certainly check this before proceeding with work on system and replace with AWG 10 if needed.
Separator switch: SurePower 1314A (original from 4WD factory, I believe.)
Solar: Renogy 12V, 150W panel on roof, Bogart SC2030 charge controller. I installed in 2017.
Battery monitor: Bogart Trimetric TM2030. I installed in 2017.
Crown 80Ah AGM battery I installed in 2017 after original battery failed the first time we took the camper out now seems to be on its last legs. Through (initially) ignorance and (later) inattention, I managed to completely drain the new battery at least twice and drop it below 50% a time or two as well. Now, even after showing 100% charge on TM2030 monitor, when we run it down to 80% or so on the monitor using lights, "furnace", fan, etc., battery voltage is low (wish I'd thought to write it down when this has happened, but it occurs to me now I could possibly get some of this info from the monitor memory), lights start to flicker, and furnace won't work.
I know I should probably get a load test done on the AGM, but I'm pretty inclined to go ahead regardless and replace it with a BattleBorn 100Ah LiFePO4 battery for the additional usable capacity. It looks like I might have to finagle the existing battery compartment a bit to fit it in, like raise the cleats that support the wee plywood cover to provide more clearance for the battery terminal connections, but this seems doable. I have BattleBorn's instructions on setting the correct parameters for the battery on the TM2030 monitor and SC2030 solar charger. I also noticed in a previous post that I can get an IOTA IQ4 smart charger module to plug into my existing IOTA DLS30 120V/12V converter/charger that will automatically provide the correct charge rates for the LiFePO4 battery.
I think that just leaves the truck to camper charging system. I want to upgrade this eventually to get more charging from the truck (bigger wires, new alternator, new isolator switch, 12V/12V charger, etc.?) , but my sense from reading other posts is that with the built-in BMS on the new battery, I could safely install it without having to worry too much about damaging it with the existing on-board charging system. Am I more or less on-base with this approach?