Have had a 12.8 Volt 200amp/hr LifeMnPO4 prismatic pack in the RV for over 3 years now. It's used in conjunction with the golf cart FLA system. Installed a cell based / pack based monitoring/alarm system the cells typically stay within 15mv of each other. With out any doubt it's the best upgrade / modification to date. 600 watts of solar, 2Kw sinewave inverter, etc. We did not get an RV to save money instead we purchased it to have a good time and enjoy the toy.
Suggest you take a look at prismatic cells/pack Vs the many smaller "C" size or similar cells that make up the plug and play drop in batteries.