It will work, i built a rocket stove dehydrating room, and it's a pretty drafty affair seeing how I used salvaged roofing and glass walls. It was a brutal first construction for a single person to do with two metacarpal fractures in their hand after falling off a roof in a midnight
canopy building session.
With all the unisulated walls of glass, and gaps in the roof the room dry's at 86-95 F. If i didn't have all that glass the tempurature would be even higher, the outside temps were around 50f at harvest times, the only thing you might have an issue with is the excessive loss of humidity over time but if your in a sauna for more than 2 hours you've probably passed out and are on your way to the next life. The rooms 8 feet wide by 16 feet long, that's a pretty swank sauna and i build it over gravel so I know I broke allot of insulation rules and it still works. One note my rocket stove is uninsulated and vents under a deck floor so all the heat is lost to the air on purpose. It's configured to burn pellet's and is disasemblable in about 50 mins. So if your not renting like I am you can be way more efficient and do something permanent.