Bikini top straps.

Go to an outdoors shop like a REI or such. Get one inch wide flat webbing and plastic parts like you'd have on a backpack. Drill and attach a footman loop to the back of the Jeep at the corners and put together. . . Will work like a charm and you can really snog it down without it continually coming loose.

 

It looks to me like a piece of rope would work just fine.


Or you could get a strap at the FLAPS with some kind of hook.

But I wouldn't know. My jeep doesn't have a top.