Don't know of a Commando that doesn't wet sump, unless it has a one way valve in place, or some other mod to stop the oil seeping past the gear sides in the pump. Personally I would not put a check valve in place, as I would worry it may restrict the flow of oil at idle and also it may fail by locking and restricting flow (unlikely, but possible).
If you carefully re-build your pump and keep the crank at TDC after riding, it should not wet sump overnight, mine seems to hold up for several weeks, if not more. I use 20-50 oil.
The most interesting mod I saw was a simple ball type valve that, when shut, the handle covered up the ign switch where the key went in. So you shut the valve when you stuck it away but couldn't get the key in until you opened the valve.
Stu.