Can't help you much with the DMS issue but, assuming you use portble propane tanks, there's a couple of things you might want to consider.
First off, the colder the weather the colder the tank the harder it is for it to push the gas out. Partially submerging the tank in a tub of warm water helps there.
Second, it's a good idea to always have a second full tank around. That way, when the first tank starts to wind down, you can just switch over the second. Then it's just a matter of refilling the first tank whenever it happens to be convenient.