I'm not sure, bit I think the rules vary from state to state? Pretty sure that in at least one state, ALL write-offs are statutory.
Going back to the
OP, or anyone looking to convert:
Statutory write-off probably helps as you only want the components;
Maybe consider the running gear from a PHEV (eg outlander), as they are primarily an EV, and presumably extra batteries could be added in place of the generator;
Or even a parellal hybrid like the Camry. Must be plenty of those around wrecked, and they're capable of running purely on batteries. Just need a plug-in charger.
You might also consider approaching the wreckers who are buying these write-offs. It's generally things like lights and panels that are at a premium, rather than the running gear.