You're the only Stealth I know of with a groove in the hull for the trampoline. Most have a series of mushroom plastic thingies screwed in the top of the hull to strap the trampoline to.

The simplest option would be to go to a larger bolt rope, maybe widening the entrance of the groove so it can fit.

Another is to try is to slide a big diameter rope inside the groove with small dyneema line spliced and stiched at regular intervals to make loops. You can then lace the trampoline to the loops. You would have to reduce the trampoline width however in order to get tension...

Or convert to the mushroom method.