John, for the Carson relight you are correct if one waits until pattern altitude at Carson. However the strategy should be to relight over spooner the moment you down to your minimum altitude, say 9K. You will need a short run and only 1-2K climb to get to a safe final glide altitude. If you run out of battery before hand you can escape back to Carson.
At least this is what I would do if I have FES.

Ramy