National Forest Pine Sap-uggg!

I camp in Colorado National Forest campgrounds a great deal in the summer. We live in a forest as well. This year the sticky yellow pine tree sap has been particularly bad on roof & down the sides. Can't get it off w/any conventional household cleaners I have. This is probably not an uncommon problem. I know lacquer thinner will cut it as well as the painted surfaces. This I have proven. Any & all product suggestion greatly appreciated.