If 70F is ideal and 66-68F might take a little while longer, what about 75-78F. Thats what the temp range of my spare bath is. Hope I'm not creating problems for myself. Is that too hot??
The highest need for strict temperature control is during the first 3-5 days of active fermentation in the primary fermenter. About 99% of any off flavors attributed to yeast happens during that period. After that, not nearly as important.
You still don't want to store your bottles above like 80 degrees, but even if you do that, it doesn't cause much harm. A high carbonation temp will actually speed up the carbonation, but isn't condusive to clean conditioning. Carbonating and conditioning above 70 might add a few more days to a week to the time the beer needs to condition, but that's about as bad as it gets as long as it's nothing extreme.
Think of it this way. In primary fermenation you have something along the line of 180 billion yeast cells in 5 gallons of solution. So 180,000,000,000/5 as a proportion. In that proportion with improper temp control, the yeast can cause a relatively significant change to the flavor profile with the off flavors they produce.
Now, you have X yeast cells in a 12 oz bottle. I have no idea what that # is, but the X/12 proportion is a fraction of the proportion you had in the primary solution. The same rules apply: get it too hot, and the yeast produce off-flavors, but since the yeast are such a smaller % of the bottled solution, any off flavors they produce are a fraction of what they would be in the primary solution. So, at higher temps in bottle carbonating and conditioning, you'll still get off-flavors, but they'll be pretty insignificant and easily conditioned out with just a little extra conditioning time.