Thanks. Yep, that sounds like a reasonable approach given your system constraints.
Heating your molesieves would help.
Adding salt to your ice water might also help a little, but you’re never going to get all your propane back passively without going colder on your tank.
If you’re using a propane/butane blend, you can figure out your current ratio using a pressure gauge and a thermometer and this handy table Propane Butane Mixture - Evaporation Pressure
See: Blending Solvents