I guess I never really thought about it, but now I'm wondering about it too. I'm guessing at a minimum, you'd have to be going someplace that can support a -38 (airport with LOA, UPT base, etc.), and the trip would have to be short enough so that you're not screwing over anybody else's currency based on aircraft availability back at Beale. Also, I could see commanders being leery of the appearance of FWA, bad publicity, or whatever, following the fiasco with the ANG F-16 commander.
Still, I'd like to hear more about it straight from somebody who's in the community.