The OP is concerned that mashing higher than intended means he'll have more a "thicker" body. On one of those brewstrong interviews with Charlie Bamforth, they talk about how it really takes a ton of dextrin, all other things being equal, to increase the "body" of the beer. So mashing a bit hotter than you wanted, by itself, will have a small-to-negligible effect on the "thickness" of your beer.
From that, and my experience, I'd say the difference between actual attenuation and potential attenuation has a bigger effect on the perceived body than any of the absolute numbers. I've had a Belgian pale ferment down to 1.010 and a Saison ferment to 1.004, with almost the same OG. The pale seemed drier and thinner than the saison.
Doing a forced ferment test gives you a number to "shoot" for. You can still mess it up, like when I overshot my pale, and undershot my saison, but at least you're not flying blind.
So back to the OP's concerns, here's what I'd do. Pull off some wort and do a forced ferment test. See how your wort ferments out as-is. If you're off your mark, rouse and warm the yeast until you get the FG where you want it to be.