Hmmm.... I'm about to send an e-mail to the author of cDOOM. It would seem that you can see sprites through 3D floors...
Certainly something that needs to be resolved before this could be made use of.
EDIT: And it would seem that both of the author's e-mail addresses are dead... :/
Bummer, he had just released cDOOM 2.07 less than 2 or 3 months ago.
Edit: found a third e-mail address for him that did not bounce back!!
P.s. Palette issues figured out for the most part!!!
EDIT: Nope, after many hours, that e-mail bounced back too. How strange.