If you want to attach an awning or annexe to your van, you will find the following useful:
Figure of 8 (Search eBay for figure of 8 plastic channel strip). Consider the lengths. Sometimes it is easier to store shorter lengths, than to buy one single long length.
Awning Kador 6mm (for sewing onto awnings and annexes). You will probably need a sewing machine to attach this strip to your item.
Another attachment system uses a magnetic strip: Outdoor Revolution Magnetic Mag-Connect Driveaway Awning Strip Connector.
Awning and wheel skirts. Sold by the metre. You could also try making your own, using a cheap plastic shower curtain.
*Please note: If any of the above links stop working, use the information to make fresh searches.