$500 for a hitch is not that bad. You'll be close for on for the front of the truck. Do a search, there are also a few bike solutions that effectively come off the pin box, putting the bikes in front of the 5th's end cap. Or there is always the top of the trucks cab.
I would never think of using the ladder - as noted, it's just not built for the bounce-bounce-bounce.
If doing a rear receiver, be very careful about the brand/model of bike rack. Only a few are designed for the bouncing, which is far more than would happen on the back of a car/truck. Your receiver will stay on, but the rack itself may fail and fall off.... You have to sometimes dig into the instructions before you find out that a particular model is not intended for RV use.
