I've got one on the side of my trailer and it makes a big difference. I had to mount it upside down because it was too high off the ground in the normal position.
I mounted it towards the front of the trailer where the frame curves in so it didn't stick out too far and become a shin buster.
Here's a link to one like mine. I just turned it upside down to get the right height and mines on the side instead of up front.
Guide Gear Boat Trailer Step - 215607, at Sportsman's Guide