[sonic]

That turnbuckle mount looks to stiff and to weak at the same time. On the original rubber mounts (that holds the transmission) there are some flex, 1-2cm perhaps. With that set-up you have 2-3mm tops. So when the transmission flex the motor can't. Something will snap, most likely the bolts on the turnbuckle. If I were you I wouldn't drive the car until a proper mount is installed (like the drawings) with same flex as the tranny, if you have the old original you're halfway there. As a bonus you get torque twist support also.

The EV I'm planing to build (still in my dreams) I will use a Webasto / Eberspächer diesel heater, connect to the water heat pack with a small tank. That way I can have full heat without draining the drive battery's. Also I can pre start the heat some 30min before take off, the car warm and ice free. Another idea I have is to rout some air tubes from the heater to the isolated battery packs, so they are also warmed up to get max amp out em.