What I'm planning on doing is measuring the width of the frame where I plan to mount it (hopefully using the bumper mount bolts), the distance to the bumper and the height of the bumper relative to the mount points. Then I'll draw a diagram with measurements.
Then I'll go to a junk yard and start looking under the trucks, SUVs and vans 'cause lots of them that have nice trailer hitches that are mostly hidden behind the bumper that could work for you, depending on how you plan on mounting it. When you take the hitch, make sure and get the plug and wires for the trailer lights/brakes.
Even if you don't pick up your trailer hitch from the junk yard, it'll be worth your while to have a look at severl different designs either at the junk yard or in the parking lot and traffic before you make a decision on the design.
Personally, I like the ones where most of the hitch is hidden and only the 2" square receiver and brakelight plug are visible.
As far as what size/class hitch you need, that depends on the weight of what you plan on towing and the tounge weight. Try googling 'trailer hitch class.' Sounds to me like you'll need a class III or IV.
If you can't find just the hitch you want over the counter or under a wreck, a trailer place nearby whereever you are can make a custom hitch to your specs pretty easily. For example, U-Haul makes custom hitches as do others.
I suppose another option, if you have a 55 + is reinforce the bumper and put the ball in the license plate cutout/dip/indentation in the bumper.
