relocating bathroom

I want to remodel an Overlander; bedroom in the rear, bathroom in the center. I intend to gut the interior, flooring too. plumbing and electric will be new. moving the toilet and shower where I want them shouldn't be that difficult.I'm a cabinet maker/finish carpenter and have friends in other trades who will be pressed into service. can't wait to get started.

also any opinions on composting toilets ?

lithium batteries ?