I iron/steam mine on the frame. Roll it all onto the back roller, attach to the front then when rolling it onto the front roller I go over it with a steam iron that I keep by my long arm. I think that if you look at utube you can see a video of Sharon Schambers doing her quilt like this - although instead of ironing she just sprays with water or starch like Dunster and some of the others. Me I don't like to wait long enough for it to dry!
As for stretching to get the wrinkles out, yes that does work to some extent but you want to be careful not to have your back stretched too tight or it is going to pull up when you take that tension out of it.