You can tow in OD. I do all the time at anything over 55 MPH. When you start climbing a hill, take it out of OD. If you tow out of OD your mileage will suffer also. I use air bags with my TT and it make a huge differance in the ride. Tranny temp gauge a must but if your truck is all stock or mostly stock but unchiped you can get away without an EGT gauge, but again its nice to have...