Kayak roof rack for low high top!!

[Istanbul05]

Hi peeps,
My tin top has now evolved to a low high hard top, sloped at front and rear and flat on top, only about 18" high. I have seen various roof racks that involve a slide system that allows you to load canoe/kayak easily then sliding up and over onto the roof! Obviously this system requires a roof rack system to attach to a T25 rim? Wondered if anyone knows a company that provides the whole system rather than me bodging together a mish mash of rails!!! Alternatively don't mind a side rack system!

Cheers Si