A wound G string has significantly better tuning stability on a Les Paul. My plain G had bad intonation, went out of tune easily, and had a nasty ringing overtone coming off the bridge.
I switched to a wound string and now it might actually be the most stable of the 6. Better tone, perfect intonation. If you're worried about extra tension making bends difficult, try a .018w, it has the same tension as a .017p. I use .020 or .021 because I like more tension. I'm gonna get a string butler when I can, but short of one of those, the wound G is the best and easiest solution to the inherent problems.
D'Addario makes single strings in all gauges. Stringjoy.com sells singles and you can build custom sets.