Have 4500# travel trailer. What motor do I need for all conditions (Flatland, mountains)

 

Under 5k is an easy pull if its somewhat aerodynamic.a small block chevy with 3.73. Gears.overdrive off on hills .add an external tranny cooler whatever you get and elec.trailer brake..to start with.no just the motor gets worked wuth the extra 2 and a half tons extra..tranny brakes and suspension.to be safe address them.