3 sport bikes is roughly 1500 pounds. Gear for 3 200 pounds. 3 adult males average 600 pound, trailer to hold the bikes 800 pounds. Rough total of 3100 pounds I'm not really familiar with the 5th gen, but I'm guessing the rear will sag badly. Manual full airbags are roughly $100 and are easy to install. Check out firestone bags. Make sure the trailer is level and loaded 60/40 weight distribution.
Pushing the bikes all the way to the front of the trailer as seen in the uhaul pictures will be too much tongue weight and only make the sag worse. If the engines of the bikes are slightly forward of the trailer axle the tongue weight should work great. However, if you plan to put other gear in the trailer shifting the bikes may be needed. If you plan to use wheel chalks mount them to a piece of plywood that is big enough for both the front and rear tires of the bikes to set on. This way you can adjust the position of the bikes, but they won't move while towing. This is because the tie downs will be holding the bikes and plywood down together. Also, keep in mind that as you put gear and people in the cab the rear will sag too.
It's a balancing act. Too much rear sag means less front tire contact patch and less emergency maneuver control. You will be ok in the power and brake department.
