I went through a couple iterations of batteries and solar maintainers until I realized I had a draw with the dead crank switch left on. The maintainer would keep up with it for a while then next thing I knew the batteries were dead. Turn the dead crank to off after every use and problem solved.
For the last few years I have had the small 230CCA Walmart lawn tractor batteries in mine. As long as I turn the dead crank switch off after use or testing they are ready to go the next time I start it. <jinx>Note the date on my current batteries is 3 years old now and working fine. </jinx>
Larger batteries may encounter some clearance issues with the unused engine mount tab on the block.
I just opened the top mount terminals and ran a bolt though the tabs on the lawn tractor batteries. Edit: I drill the holes out to 5/16" on the battery tabs.
I don't bother having any kind of charge maintainer on the batteries anymore. I do run my unit under load for an hour every month to make sure it's ready when I need it and to keep the batteries charged.