I think you've pretty much already answered your own question. If you
really want to get as far off gas as you can, then you need go bio-D. That also lets you keep your towing/hauling capabilities.
Hybridizing anything will, as you know, only give you so much electric range/assist, and you have to subtract battery weight from your hauling/towing capacity.
Use one of the pure EV's go go around collecting the WVO.
