I like the design of the box, but I am not sure this would be best set up (If you will be placing this in the back of your Alpha). I just took a look at the dimensions and I am not sure it will fit because of the height. The reason why I say this is because the back of the rear seats are not flat in the back. They are slanted, so the higher they go the less room you have. For reference I have the Smittybilt 2763 storage box and it just barley fits (It is 15 inches high). The box you are looking is about 25 inches. Since you can actually go to the store and test it out, I would do that if you are really considering it. Here is a comparison of the dimensions: Pretty similar.
Smittybilt Box 40 x 15 x 24 inches
Lowe’s Box 40.5 x 25 x 24 inches
Another possible downside to this box is that you will have to take the whole thing out if you want to use the table which will be really heavy since it takes up the whole rear storage area and will probably be loading all your gear and tools in there. In addition, you will have to take out anything you have on top of the box like backpacks, camping chairs, etc. Back when I had my 2006 H3 I just used a cheap power packer storage box and it got annoying. For one, you have to pack things vertically, so anything at the bottom will be hard to get at. Also you have to consider if you can even open the lid of the box inside the truck. Again this is assuming that you are putting this in the back of your H3 and not on your trailer, but some principles things may still apply.
Another solutions that you can consider is the Ebay Molle Tailgate which some H4O members did years ago:
http://www.molle-platform-solutions.com/product-page/hummer-fold-down-molle-tailgate-panels
