I'm getting ready to tackle this project too. Thanks for the inspiration ronjenx!!

I do have the Wood's tub enlargement kit and the Tuffy cubby cover. I'm wondering if I can keep the cubby cover to further organize the gear. I may have to leave the backend open to make it work. What do you guys think?

 

That wouldnt be a bad idea. If your making it out of wood i wouldnt use cheap 2x4s like i did as they tend to split easily when screwing into them and i would get some L shaped brackets to reinforce the corners where the 2x4s attach to each other

 

I think you will need to make two door cover with a cross bar in the middle instead of the front so you can open the tuffy cover, sorry for crappy sketch .

 

I was thinking along the same lines with the cross bar. However, I believe I can still do it with a single cover. If you take the front cover you've drawn and move it to the bottom of the cross bar and lose the flap, it will represent how the tuffy cover will stay in place within the storage area. The cover can still be full length. I think.

I'm also thinking of making it out of 2x6 aluminum tube for a little extra strength and height. If I ever used it as a tent substitute camping, I would want to be certain my 220# plus the wifes 110# wouldn't bend the supports.

 

Have you seen the pics of my box pics are on page 1 it's a little different but you might incorporate some features and it's plenty strong , remove the sliders and the long center support and make it a little longer , cut a hole in the bottom for the tuffy opening and keep the fold out floor panels

 

I moved the pictures of bolting down the frame to the first post.

 

I was eyeing that up as well. It's going to take me a bit to figure this one out.

 

Nice work ronjenx looks like the same lows outdoor carpet I'm using

Here is an other crappy sketch to mull over

 

I used your very excellent instructions, but built mine out of wood 2x4s because I already had some. I've been thinking about the 3rd seat option for the grandkids also, so I combined the two. I installed four eye bolts through the tub behind the box and used motorcycle tie-downs to fasten two car seats securely on top of the back of the storage box. Now I can carry four adults and, with a third car seat in the middle of the back seat, three grandchildren. This forum is the greatest.

 

I can't quite imagine what it looks like. Any chance you can post some pictures?