If the ARF Stinger is built like the kit stinger. Then it has a built in weak point, all stingers seem to break there. The point is the forward point of the wing saddle, just look at it from the side and you will see what I mean. see if you can get some sort of doubler to beef that point up.
The stingers all fly great, from the smallest to the biggest.

I doubled my 120 size wing saddle and have been banging this poor thing around for over a year with no problems.