tie-down

I have a genuine kombi rear floor for sale with the 6 lashing points included. The floor cutouts are for the 2+1 seat set up. You can cut additional holes if your seats are 1+1+1. The van didn't have a bulkhead so the floor will run perfectly to the front rubber floor. It was from a super low...

I've noticed there are two holes with what looks like M8 threads in around the wheel arches on the interior, does anyone know what they're for? I'm planning to have the van carpet lined and not sure whether to cover them up.

I'm looking to make something similar to this set up although it needs to be light enough to remove easily & not quite as fancy - just a bed frame which flies over the wheel arch with some storage room underneath for my bike kit. Anyone on here made this set up or seen one with a MX Bike alongside?

Do any fellow bikers tow their bikes on a collapsible dedicated trailer?

Does anyone know what the size is of the bolt hole is above the inside wheel arch ? 10mm x 1.25mm pitch is what the size is of the bolts on the lashing points but is too loose and 12mm x 1.75mm pitch starts but gets too tight. Any ideas?