I started to concoct something similar - even have the Workmate. I need to go through with it. Thanks!

I like the idea of a small table that can attaché to a Reese Hitch. A simple
Camp Chair and you can work up loads at the range! I long For the days when I am able to have such a relaxing time at the range, now it's grab all the crap you can, hurry down there, shoot as much as you can since I only get 4-5 range trips a year and hurry back home so I can do what needs to be taken care of at home! Hopefully in the next year or so, I'll ne able to walk out the back door and test out hand loads!

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Used a Workmate for years before getting a proper bench set up in my basement. Loaded many thousands of rounds through my Dillon 450 on that old folding bench, but did not put an accessory top on it, just clamped to the small original top and started pulling the handle.

...using a Black-n-Decker Workmate, with the press and powder dump mounted on a piece of 2x12 such that it could be clamped in place on the top of the Workmate using the vertical clamp. It was very solid, and left just enough room on the top for a loading block. We took it with us to Montana on a prairie dog trip, and set it up in our cabin. It turn out we didn't use it that much (we had LOTS of ammo!), but it was nice to have it handy. I've toyed with revisiting that idea for a portable loading bench to use up at my range.....

It would be easy to make something like that for a lot less money if you are a little handy. I once built a small table by laminating 1x2's that I salvaged from old pallets. With a couple of 2x2's and more 1x2's I made legs for it. I had it around our house as a side table for about 30 years. Last time we moved my wife made me give it away.

I had an old reloading stand that my uncle made when I was a kid. He welded a piece of pipe on an old car flywheel, and welded a piece of plate about 5" x 8" on top. Bolt the press to the plate, set the flywheel on the floor and you are in business. Portable and didn't take up much space, but heavy.

I've found that lightweight tables don't resist backwards movements of the arm very well. The flywheel didn't and I suspect the workmate wouldn't either, but not much you can do about it.

For range use I think you can buy the cheap Lee presses, bolt one to a small board, and clamp the board to whatever table is available.
http://leeprecision.com/reloader-press.html

But then Lee makes a fully hand press that you can use without a table.
http://leeprecision.com/breech-lock-hand-press.html

When I went to Lee's site to find links for the above, I see that they make their own small and portable loading stand:
http://leeprecision.com/product.php?productid=3877&page=2

I've got an old Rockchucker and one of the little Lee presses (for decapping only) mounted side-by-side on a sawhorse, with a T-shaped crossbar made of oak 2x4s. Presses are set up for downstroke, and I put a couple of old rubber floormats under the legs to keep the whole works from sliding around. Set it next to my workbench (big old lawyer's desk) and sit in my big swivel chair to work everything.

When I get tired I just lean back and take a nap......