If approved, the vehicle being rented through Outdoorsy is covered by Outdoorsy's insurance policy. That means that if you rent a trailer to hitch to your personal truck, only the trailer is covered by Outdoorsy insurance. However, coupling both vehicles will not void either insurance. If a vehicle is involved in an accident, whichever insurance is in place for that vehicle will be used.
A small daily fee (via add-ons) can help out for any extra "wear and tear." Always make sure to know the weight of what is being towed vs the weight threshold of your vehicle.