bedslide to hold tent and mattress a la Adventure Camper

I love many features of the Adventure Offroad Campers, (as well as the Camprites) but can't afford either at the moment.

I am hoping to build a poor man's hybrid version using my current off road 7x4 trailer that we currently use to haul our tent and all our gear.

My idea is to have a "slide" that pulls out of the back/rear of the trailer, holds a 2mx1m platform supported by adjustable legs at the end. It is hinged longways to a second 2m x 1m piece to open like a book (or preferably but harder to envision, that the top piece slides over and sits next to the bottom piece. This would allow the tent to be stored on top of the second piece and cut out one step in setting up) with its own adjustable support legs, to give a 2m x 2m solid platform on which to pitch my oztent with mattress to give me the effect of the rear slide out bed on the Adventure Camper.

I hope these thousand words can paint the picture!!

The legs and platform pieces are easily imagined and constructed. A bit harder is the slide mechanism and I'm wondering if anyone knows of a manufacturer that sells such items ready made. I haven't had a lot of luck googling and I thought someone else on here might know just the place. I am in WA so closer to home the better, thanks,