Robin I have a 4wd truck and it is not a problem. We leave the hauler on all the time. Groceries, lumber, recycle stuff, Christmas trees, and other things we want to haul are loaded in the back and are safe and covered.
If we have to use it to haul the horses in an emergency we do not have to attach the trailer, but just load and go.
I too was reluctant as to if they would go up the ramp initially. The first horse I went to pick up he ran up the ramp and was waiting for me in the trailer!
We have an earthen hill at our home that they can walk straight in, but I actually think the walking up the ramp has advantages as well.
I LOVE the enclosed unit (I had a stock trailer before and hated the wind). I love the lights inside and out. There is a ramp light for loading. The horses look down on us and feel safe. I can look through my back window and know what they are doing without pulling over. I can drive the speed limit when appropriate as I am not pulling a trailer. It has the standard trailer windows made for full size horses which are easy to operate and I can control the air flow based on the conditions at the time. It is an excellent way to move a mare and foal.