It is an interesting scenario. It obviously wasn't necessary last year, because of the 1-2 punch at SF of Pierce and Posey. If you remember back 5 years to February, 2003, some people would say KG's real "I'm here." announcement to the basketball world was his All Star game performance in which he dropped in 37 points and took home MVP (although anyone who cared about the happenings in Minnesota realized how dominant he was by 2000 or so). A good chunk of those points, in OT and 2OT, came while playing SF and having the blatantly too small and helpless Vince Carter guarding him.
Or remember back to earlier that same season, when after a narrow loss to the Wolves in which KG was defending TMac for a majority of the game, McGrady (32+ ppg that year) came away saying that it was "the best he had ever been defended in his life".
Nonetheless, like Who said, 5 years ago.... sure. But KG has lost a step since. For the 10 minutes per night scenario you suggested, I could see it working, depending on the matchups. I still think he is fully capable of playing spurts of lockdown D on the perimeter. I think a lineup of House, Ray, KG, Powe, Perk would have enough perimeter shooting to work and create some matchup problems while Pierce rested, but it'd be tricky for Doc to balance it all out to make it work. I think the best hope is for Walker/Giddens to develop quickly over the first month or two of the season.