Mounting a Reese Explore roof top carrier on a Twist or Bullet Speed canvas top roof is very easy. No need to go fabricating parts either. Nor spending a bunch of money either.
Here's what to get:
Reese Explore Carrier. Less than $90 at Walmart -- 24087297
Clamps. A set of 4 clamps from House Tuning. Amazon or e-Bay costs less than $25. Get the clamps that will fit 1.625 pipe. House Tuning 1.625 inch Roll Bar Clamp Tube Clamp BracketRoof Bar Clamp for A... | eBay
Four 3/8" Bolts from your local hardware store. On my 1st gen Twist top I had to add a 1 1/2" spacer to the front clamps but on my brothers new Twist top no spacers were needed.
So to summarize a carrier, 4 clamps and 4 bolts and you're ready to pack up for some traveling.
Note: I can't take credit for this system thou cause I talked to someone at the Slingshots in the Smokies who had done this.