Anchoring shelving in the sleeper

So, I'm trying to plan a modification to my truck and was wondering if anyone had some practical ideas of how to build/anchor a shelf in the sleeper berth. My intention is to remove the second bunk and replace it with a "U" shaped shelf around the interior perimeter of the sleeper. I don't have a problem with the actual construction of the shelf, my concern is more of how to anchor it to the wall so that it can support a decent amount of weight without drilling through to the outside. Anyone have any ideas, or know how thick the walls are so i can get the correct anchors?

Thanks,
Razorwyr

 

Bakerman, The problem with that is i want it to be open and i'm fairly tall, i can't sit up in the bottom bunk comfortably. I want to be able sit and relax without being hunched over.

 

Thanks, but I haven't bought one yet, so not sure. I was wanting to buy a 2011 387 in March, but circumstances have changed a little and I may be getting a 2012 Cascadia this week. If I go with the Cascadia my plans may change as I have only ever driven 387s and 587s. I like the room in the Pete, but the truck I was supposed to be in until March I was forced out of and I don't feel like moving twice. I don't like the looks of the Freightliners, but I have heard very little negatives about the 2012 Cascadia and quite a bit positive, so I may go that route. I have a few more questions about it before I decide for sure.