In the model 3 at least, the rear doors can also be opened without power by pulling a cable. Not as obvious as the front doors, I’ll say, but you will be able to get out.
https://www.tesla.com/ownersmanual/model3/en_us/GUID-A7A60DC7-E476-4A86-9C9C-10F4A276AB8B.html
Should work, at least as far as the latency is concerned. Faster ram can be accessed at slower speeds.