I have heard of that happening - bikes on the ladder causing some damage. While the bikes and brackets might not weigh much, their weight can translate to A LOT when hitting a massive bump like railroad tracks. The kinetic energy can be a wowzer.
I considered a front hitch receiver, but I think my bikes might cover the headlights. In some states, this could be a violation.
Check this out. This is a link to a rack mount system that installs on the front of your fifth wheel. They have brackets for short beds or long beds, and is good for 2 or 3 bikes. The drawbacks are the height of the rack and the difficulty of removing the bikes if you are hitched up. Look up the 7000-5W or 7000-5W-XL:
http://www.toppoprails.com/fifthwheel.htm
I have been toying with the idea of my mounting my Yakima rack system on my TV roof. I have seen other members that have done this. I am preferring this because for me all I would have to buy and install would be the landings since I have everything else - mounts, rails, and bike runner/holders. Obviously, with this solution I am not worried about the height of the rack.
Good luck with your solution.