When I run across this issue, I usually put vertical support posts to reinforce. It's easier with core wood, but can be done with base level posts too, it just looks more messy.

If you want to get real pretty, and I'd wait until core wood or better, put in beams between posts. Once you get to where the roof tiles are highlighting yellow, stop and put the support shell in place.

Post, then beam, following roof line, and then add the post at the , now hanging end of the beam. Rinse, repeat until you've done the entire perimeter of the roof line. I usually only have to do this once. I have been putting a fire place and chimney in the center of a house too. So that often functions as a center roof support, and eliminates having to repeat the process a second time. Depending on the shape of the house you're building, it can be done so that it looks completely natural.