Grippa sell a
Grippa clamprack stud at different lengths about £2 each
And a metal tube clamp which will clamp there pole tube or a gutter tube for about £7
I use two studs and two clamps with a tube in it per pole Choose length stud how low you require the pole tube
In the cross beams of the van there are holes the studs are well suited to go up into and tighten on themselves, the clamps have a threaded section which just threads up onto stud
I also put one tube either side of the van then bolt a section of metel tube to each clamping either side van forming an area where I can put a ladder inside the van out of the way also space for gutter tubes and also the modular poles when needed