Do yourself, and everyone else on the road a favour, and take a few hours to install a brake controller onto that truck!
You'd probally fine if you were only going a few miles, at a reasonably low rate of speed, but on the open highway anything can happen, and you'll need the ability to panic brake.
Momentum type brake controllers (Timed controllers are junk, don't waste your money) are a few hundred bucks up here, and can be moved from vehicle to vehicle fairly easily. Well worth the cost and effort, and the costs are relatively little in comparison to a major fatality accident if you can't get stopped fast enough in a panic situation...
Installing them is easy! You just need some heavier gauge wire off the distribution block / battery to an inline circuit breaker on the firewall, to the brake controller unit, then from the brake control unit back to your 7 pin connector, a ground wire to the brake control unit, and a wire to the brake switch.
Also need to run another heavy gauge wire from the distribution block to another breaker, to the 7 pin connector to provide a power wire for keeping the trailer's battery charged. The rest of the wires on the 7 pin connector are already out back, including signal lights, tail / running lights, and reverse lights, and the frame rail for a ground wire.
You should be alright without the torsion weight distribution bars, just lift that leg up a bit higher than it is in the pic, and slow down for any obvious bumps so you don't bottom anything out.