Two suggestions:

1. I put my dough, covered with a damp cloth, in the oven along with a pan of very hot water. The hot water seems to keep the oven at the right temperature for the dough.

2. Don't laugh too hard at this one! A friend's mom, when I was having trouble with her bread recipe, suggested that I put the bread in bed, under the covers. It actually worked, but you have to make sure the bowl is big enough and you need to check it to make sure it doesn't rise and get stuck to the blankets. She also said that electric blankets work really well.