Isolated DC/DC Step Up Converter?

I'm building a bit of any odd hybrid system that involves a small capacity 20S battery pack installed in a vehicle that is continuously trickle-charged by the cars existing 12V infrastructure. I've been able to isolate every other aspect of the "HV" system but don't know how I can charge while maintaining galvanic isolation. A traditional boost converter will link chassis ground and HV negative which is what I am specifically trying to avoid. I have a BMS to balance all the cells and prevent under/over voltage. I just need to figure out a way to step up ~12V to 80V with about 200W of power without sharing a common ground. Any suggestions would be welcome!

Thanks!

It's clunky, but the 80VDC output of an unisolated boost converter could be used to power an isolated switch-mode PSU (most will run with DC input in place of mains AC).

An isolated boost converter would certainly be simpler, if such a thing can be found at a reasonable price.

Only 16V up to 60V, but maybe you can ask for a modified version?

https://www.fraron.de/en/dc-dc-converter/24v-to-48v/