Sleeping in an enclosed space with any gas burning device is dangerous!
My experience with propane above 8K feet is poor. When you go above 10K, I think you will have problems.
I went back to Liquid (Coleman) fuel stove, lantern, etc. for this reason when camping at elevation. But some propane devices work better than others, so you may get lucky.
A family we know has a cabin located at 9600' near Bridgeport and use propane, but their neighbor uses old liquid fuel catalytic type heaters?
If you have room, bring both types! If not, propane will work, but expect lower performance.
Doug