Remodelling a jockstrap into a thong could work if you want a more elastic pouch for daily class. However, I've seen the result when someone has tried to use a jockstrap (remodelled) under white tights for a performance and it wasn't a pretty sight! He didn't dye it flesh color, so the white waistband and pouch were extremely visible. You could even make out details of the pouch material.
I'm surprised you can't find a dance belt to accomodate your 32" waist without getting that squished waist look caused by a too-small waistband. 32" is normal waist size.[/i]