Have had one on the boat trailer for about 2 years now.
Works very well.

 

I've got a parkit360 for our travel trailer. It works well.

 

I only have 20' in front of my garage and can't swing the front of the truck around so have to use a power dolly to put the trailer to bed for the winter. You do need adequate tongue weight (mine is 833#) to have enough traction to push up a grade. The electric break control handles the downhill.