When we first built the van we used a fairly standard Fiamma single tube table mount with a home made table. It worked, but it was heavy, wasn't particularly stable, and it was awkward to leave up, so just didn't get used. We looked around for an alternative and eventually came across the Lagun table leg
This was really intended for use in the cockpits of sailing yachts but looked ideal for us. It wasn't cheap, and we got it from a chandlers together with a lightweight table top. The following pictures show its mounting in our van, but the Lagun website gives much more information.
The mounting system in very stable but also very adjustable, meaning that the table can be put in place, the height adjusted, can be swung out of the way easily, and the clamped in place to use.
A slotted box was built and fitted at the front of the van to hold the table when not in use and made carrying it and using it so much easier. The table support has a fitting so that the leg can be stored with the table when not in use.