No one has given you a solution yet, so let me suggest something well outside the box!
My process, invented in the '70s but recently named Ferric Gum, can result in a fairly glossy image whilst the paper support remains in its natural state (normally not glossy).
The process is like Gum Bichromate but in its basic form it is positive working. At present there is also a problem concerning clearing ferric hydroxide from the final print. This needs to be solved!
There is an article about this process at
http://www.alternativephotography.com/w ... um-process
Please let me know if you would be interested in using this process or any of its variations. But I will understand if you think the difficulties would outweigh your desire for a glossy image!