I'm in a similar position as the OP, looking to buy a bunkhouse in either a travel trailer or fifth wheel (although I'm still two years away from the purchase I like to research the heck out of things). Here are my thoughts for what they are worth.
There are certainly great bunkhouse floorplans in modern day fifth wheels. In fact, I'd say there are more interesting ones to choose from than travel trailers given there is generally more room to work with in the fivers. Jayco in particular makes some very neat double over double bunk designs.
I also really like the idea of a fifth wheel in terms of easy hitching, safer towing, and (for me I think) slightly easier backing. But I'm convinced that my family will opt for a travel trailer for two important reasons: having the truck bed open for bikes, and fivers tend to cost at least 7 grand or more than the equivalent travel trailer. Also, the height of the fiver means having to be more paranoid with trees and low underpasses.
Just some things to consider.
