Would there be any negative effects from running all-thread though the back of my box directly into the cab of my truck.

The back wall of my truck is already threaded and I could strongly secure the box this way. But Im wondering over time will I get leaks or put to much stress on the MDF. I will be using 1in MDF more than likely. I would seal it and also use a 1/2in rubber mat between the box and back wall and floor to help with sound deadening and vibration.

I also will be using the back seat metal bracket to mount the floor to, I can also run allthread through box and floor threaded directly to the metal brackets.

This will be a semi wall and will probably make beauty panels to give a wall effect. Any other ideas? I hate to drill through the box as I am always concerned with leaks after spending hours building a box

just seal it up with some silicon and you'll be fine

What about flush mounting flange collars instead? That way you don't have to drill a giant hole in the box. Yeah you can silicone it but it wouldnt be much different than making a hole for a terminal cup. I've siliconed the help out of those and used a gasket and they still seam to leak over time.

We use some flanges at work and they are low profile and pretty nice looking.

Thats what I was wondering about. Any links or pics would be great. I will start building as soon as I figure out how I want to secure it.

Our parts guy left so I can't be sure where he got it. I believe it was from McMaster Carr.

I did find a pic but the places I saw online were places I've never heard of.