[Richard]

There are at least a dozen or more coaches that have been owner converted to Li Ion. The conversions range from fairly straight forward 12V drop ins, to one elaborate 56V system.

Depending upon the inverter/charger in your coach, you may or may not want to change that to permit the charging profile you desire.

I don’t think you want to use LiOn for your chassis batteries.

The amount of modification and complexity you may encounter depends on the size of the bank you install, whether or not you choose to charge them from the alternator while driving, and whether or not you want to run the AirCon off the batteries.

There are several threads in the electrical section on this topic.