Fender bassman speakers + 4x12

[Marble]

Gotta big show coming up, I want to play my bassman (4x10, 8ohms total) with a Marshall 4x12 (4 or 16 ohms, or 8 ohms with only 2 speakers...).

I know the speaker jacks on the bassman are wired in parallel, what would be the safest combo to use with my bassman? 8+16? Equals about 5.3333 in parallel, closer than 8+4. I know 8+8 would be fine, but I would like to use all 4 speakers.

My friend has a Super Reverb (output transformer changed to bassman, and also its output impedance is 8ohms,) he combines that with an 8ohm 4x12 with no problems. That load is 4 ohms I believe...

Also this will be at max power, bassman cranked to the max.