There are plenty of people who are doing Ambrotypes and Tintypes (same process on black japanned tin) the traditional way. There are texts available and workshops you can attend, and resources for the supplies needed. Why would there be a need to replicate the results with a gelatine emulsion, when you can do it the "historically correct" way?
Because I'm doing pinhole photography in 11X14 format and use exposures of 40 minutes to 3 hours or more, thus wet plate collodion is not an option for me, and I have no plans for putting a lens on my camera just yet....
I suppose it is possible to do a contact print on glass and put a white or gray board behind it. Wouldn't look the same but might be interesting.