I agree 100% with the dually suggestion. A 5th wheel puts all the load right on the rear axle, dual wheels will give a stable base to spread the load on, plus the safety of having 4 tires on the axle shoudl one blow out. As far as clipping goes, passenger car brakes are still passenger car brakes, not rated for heavy towing. Same goes for 1/2 ton brakes. Compare them to 1 ton, or even 3/4 ton brakes. Realy, most 1/2 ton brakes up to the late '90s aren't much beefier than their passenger car counterparts, in some cases, the parts interhcnage ('88-'98 C 1500 compared to the '89-'94 Caprice/Impala for example).
Here's something else not touched on, tires. the standard 4 ply tire (P rated or B range in a modern radial) would be grossly overloaded, especially with a 5th wheel. Plulled plenty of them off that were worn out or blown out from being overloaded. You would want at least a C range (6 ply) or higher, depending on what size you're running. 15" are pretty much limited to a C range these days, you'll need at least a 16" to get a D (8 ply) or E (10 ply) tire.
Better to go overkill and be safe.
