The only EV battery enclosure which I have heard of with an isolated mounting system is the one in the Ford F-150 Lightning... and that may be as much for torsional isolation (to handle frame flex) as any other reason. GM is not isolating the battery in their EV trucks (which have what is probably a stiffer frame), Rivian is not isolating the battery in their truck (which has a frame which is stiffened by the body), and Ford itself doesn't do isolate the battery in the any other model (including the E-Transit).