We'd like to install a see thru propane fireplace in the wall between the master bedroom and bath. The wall is the standard 4" (5" if you include the drywall).

The fireplace needs to be flush with the wall on the bathroom side leaving whatever is left to protrude into the bedroom. Obvously additional framing and and a mantel are going to be needed.

I'd like to keep it as slim as possible. The slimmest depth units I've seen so far are just under 22". Any in the 14" range?

Also, bottom vent would be a plus as there's a crawlspace above the floor for all of the sauna and spa equipment with access to the outside.