There are some F-150s that can tow up to 8000 pounds. If you have the 3.5L EcoBoost V6 with the max towing package installed, it can tow up to 13,000 pounds, which gives you plenty of towing capacity for 8000 pounds. The 5L Ti-VCT V8 has a maximum towing capacity of 11,600 pounds, which would also be enough.