I sold my first TT with 2- Trojan t125s on it after 10 years and still going strong. Bought 2 T 125s for my next TT just sold that and went to a fiver. We dry camp alot, so I added two more. Now have 4 T 125's. I expect to get at least 10 years out of them. The trick with flooded batteries is not to discharge them more than 50%. If you do then you will shorten the life dramatically. Yes Trojans are expensive $450 for pair but with a 10 year life and No Hassles $45/year works for us. Also have a tri-metric 2030rv battery meter. We just came home from 7 days with out hookups along with solar never ran the generator. Two T125s are 240amps so you get 120 amps. 6 volt batteries are larger than 12 volt batteries as such it takes them a while to drain down as the plates and cells are much larger.
Happy trails