If your fifth wheel is typical, in that there is a separate 30# tank on each side, then if you trace the lines they probably come together at a manifold. Many have additional ports that are just blocked off. From here you could plumb an additional line with a QD.
I've already done my grill conversion, removing the regulator, and installing the QD male end to hook the hose to. I was able to order a 25' gas line from Amazon
here, and add the QD fittings to both ends. I also ordered one of
these so that I could still connect a standard 20-30# tank if I do any tailgating.
Here is a pretty good DYI link with photo's and part #'s that I found helpful:
http://www.forestriverforums.com/forums/f68/kchinths-apex-288bhs-mods-102353.html#post1121560Good luck.