To the OP - you never say how old your batteries are other than a couple years. If they are still good, why replace them just to get something you can lift? Just disconnect and leave in the trailer - or is there a reason that is not an option? If your batteries are not very old but not charging properly anymore, why? Have you used battery power to a point where you are damaging the battery and not getting proper life out of them? If this is the case, going to a single battery will be harder on that 1 battery and damage it quicker, also possibly leaving you without power if you drain the battery to a lower state. Something to think about before you switch to a single battery. But, with the battery you are choosing, you can always add a 2nd. I went the route of 2 6v, but I like to boondock vs apartment complex camping.