Phil do you have any cold hardy info on the Panzarella varieties ? I have a Panzarella orange in the ground here & did not have any damage this year from the night we hit 24 F. How about the lemon ?
Sulcata sweet lemon I believe is the same as Sanbokan correct ? If so this variety is very hardy, mine has never had any freeze damage & the fruits are larger than grapefruit but very seedy.
I may take you up on one of the Whittaker' Golden grapefruit, I just have to find some more room for one...