you slide projector guys are funny.
how will the OP sell framed matted "gallery prints"
from a slide that is being projected ...
dupe the slide and sell a projector with it ?

while it may be true, there is nothing like a projected slide .. it won't really help the OP with the issue at hand.

i'd go with larry, garry, and kintatsu advice ...

drum scans and a close relationship with the lab, and / or the traditional printer in germany seem like the best route.

unless of course the these respondents are suggesting the OP sell a series peep shows of his work .. you know 400$ a peep of his projected slides ...