Hi Taylor, I bent Mahogany for my outer stems. The rear stem (pictured below) was a tight 90 degree curve and I got some splitting there. I was able to clamp at the split and keep things under control; I filled the small gap with epoxy and no one will ever see it. I don't know my specific species but Mahogany in general does not bend very well. In my experience, it tends to crack/break around small burl areas in the grain that are hard to see.

Your heat source is not the problem. Stay with soaking and the propane burner but reduce strip thickness down to 1/8". You may be able to control cracking by bending cedar along with it (kind of like a splint) or doing it in smaller sections. You might also try bending slower... In the end you may want to go to Walnut - it bends great.

Good luck with it,
Chip