Best Truck Camper AGM battery?

Btw, you're not really gaining anything IMO except poor cold weather performance from a Lifepo4 battery on a cost benefit ratio.
They don't have more aH and the cost is commensurate with cycle life.
Buy a $300 battery that is rated 1000 cycles or a $1000 battery rated 3000-4000 cycles.
Nothing in life is free.

Unless you have trouble reaching the battery to keep it serviced, the flooded cell is the least expensive option. measure out your battery compartment - You may be able to squeeze two 6v golf kart batteries in there and increase the the power density.

I am lucky enough to get free 5 year old server room power supply batteries that are AGM. They last another five years before I get another set to replace them. The day I actually have to buy batteries will probably give me sticker shock...

Thought you had your wheel wells stuffed with extra batteries?

Think about total cycles this way.
How many times you going to discharge it per year?
And how many years will you realistically have it? Appears you've had a multitude of RVs over the years. Are you going to need another "10 years" out of this rv and battery setup, for whatever reason?
Using 10 years as a baseline for about the longest you'll get out of a battery with good charging practices, care and a bit of luck, 700 cycles over 10 years is about 60-70 days of camping, draining and recharging. 100 cycles is 100.
Maybe it's 2 times a day if you're using a lot of power and spending your day firing up the genny multiple times to recharge. In which case you'll use up the battery before it dies of old age or misuse.

I'll throw out Odyssey batteries as the $300 each option that I've gotten the most life out of 2 different pairs of.