It looks like you have the narrow rail installed, you will need the one that is about an inch deep, to better reflect the trail rail system. Once the rail is swapped the clamps should fit.
Might not be the direction you’re going in, but the softopper has been through some serious Florida storms at Highway speeds, and folds right up to the bulkhead for full bed use.
If you go just North of St Augustine Beach, through the town and over onto Vilano, head to Porpoise Point, open Sandy beach, lots of Jeep’s, few Gladiators and just chill for a few hours, or the day. Local spot, sorry for the image, but my annual sticker is on this one...
I considered this one (price), but as it has the sewn in ground sheet, you need to empty the truck to instal, the others allow you to leave your gear in and frame over it, which in inclement weather is better, for me. It all needs to come out eventually for sleeping, but set up and tear down is...
Going through the same, although the Datin rack not ordered yet. I have installed the rail and ordered from Softopper the rail clamps to hold it down, they are about $6 each but with shipping it came to around $40 for the 4.
as the lid is aluminium I also fastened two washers inside the lid panel, and used magnets attached To the Velcro for fastening. Not a fan of exposed Velcro on the trunk lid.