be very careful since obviously your current strap setup is not holding very well.
May I suggest running, if safe, down the road with your tailgate down all the way to see what is going on back there easier with your straps, etc.
If not that, then 110% for sure while backing up, as I do EVERY single time with my smaller triton ATV88 trailer, put the tailgate down ALL the time when backing up in reverse since is so much easier to see how the trailer is moving. With tailgate up with such a small trailer, is very hard to guess since cannot see much at all besides the cycle or ATV on the trailer is all. I know it sounds common sense, but please do it EVERY single time or you will regret it sooner or later. Is not that hard to stop, put truck in park, get out and open tailgate before going into reverse.
Now that you've said that I remember I have a notched insert I can put in place of the tailgate that I can see through. When trailer'ing I am just going to use that. Thank you!
Your welcome, anything we can do to keep another Valk in operation. I also try not to trailer at night since one ATV trip on interstate I hit a few large potholes/dips in the road and never bothered stopping and checking soon after. Luckily, the interstate doing 75 mph is all straight, since I had my 2 ATV's mounted sideways with NO cornering needed since although the ATV's were in park and hand brake always set firm on, a hard corner could dislodge them sideways off the side of the open/flat trailer. I got back some 100+ miles later in the dark to find out one of my straps snapped from one of those rather large bumps in the road. Just lucky I did not hit anymore larger bumps since if the rear end of ATV which strap broke hit a few more large bumps, the rear of the ATV could have slid off the back of the trailer since having only like 4-5" tops to spare on the back edge of the trailer back edge side of wooden floor vs. atv tires.
Always, please stop every so often say every 50 miles or less until you find out that the straps are going to hold, especially in the dark night time trailering.