Here in Puerto Rico we have the same problems. Nobody carries Powermax, and if I need it, it comes by boat since it is considered highly hazardous.
In the states NO ONE wants to ship it. For many years we've used Propane with excellent results, even though the temp. here runs in the 85-90 degrees.
I asked the guys from Jetcat and they told me that propane can be used, no problems. So we'll continue using what we can get here" Propane.

Hector