As I know nothing of the Mustang 50, I cannot say, but I am familiar with the G45 and the Giant Stinger.

It will fly very well with the G45. Watch the balance as the plane was basically desinged around the G62. With the G45 it will be a straight sport flyer. Built lightly with a G62 it has strong vertical performance and can be a real Hot-Dog machine with big throws.

Depending on the builder and the wood in the kit, I've seen these come in from right at 19 lbs to 22lbs. At 22 lbs, the G45 would still fly it well, but with a lot less spirit than 19lbs.