I'll close out this chapter in things that were untried. It works!
The pork tenderloins, which were marinated overnight in a buttermilk, spice and flour mixture, really picked up a thick coating of the marinade. I put them directly into the breading mixture and let rest in the fridge for a couple hours on a cooling rack. They were deep fryed and the breading came out perfect. Not a speck missing. I can't say if pan frying them would have had the same results, what with flipping them and all.
I can only guess that the flour in the marinade, adding to its thickness, had something to do with skipping the first step in the usual dry-wet-dry breading method.
And no, no breading or mariande was saved for future use