I've been debating doing this for quite a long time with my bus because of how obstructed the passenger side of the engine is when it comes to maintenance and repairs. With the radiator being on the passenger side, the power steering reservoir being on the passenger side, all the hoses stopping me from coming up from underneath, and the AC bracketry stopping me from going over the engine; there was just so much stopping me from getting over there. This left me nervous because I couldn't access the fuel filter or the fuel drain valve, and I couldn't access the cold side of the EGR cooler, which is one of the known failure points of this engine. Now I'm sure I could have reached it all with some careful contorting and extreme discomfort but I felt like I shouldn't have to go through that. So here's what I did so far to remedy it:
I decided that having a small hatch, large enough for one arm and a decent line of sight, hidden under where the bed will be would be a good call for any future repairs. At the moment it is a 1ft x 1ft square, although I do plan on extending it about 4-6in towards the front of the bus, because at the moment I can only reach the fuel drain valve if I stretch and the whole point is to make it more comfortable to work on.
In case anyone was curious: between the two pieces of sheet metal is 1in thick sound deadening material and some support struts running parallel with the length of the bus.
Future plan is to extend the length of the hole as previously mentioned, as well as create a frame for both the opening and the hatch. I had planned on using 1in square tubing but after looking at what is currently supporting it I decided that was overkill. So now I think I'll cut the square tubing into c-channels and use that. I'll only use half the material this way and it should still be plenty strong enough. I'll use some sheet metal from the ceiling to make a 1in oversized top for the hatch on a hinge. I wasn't planning on putting on a lock since the bed will be on top of it. Any questions, comments, or advise is welcomed.
Also, this is my view from the hole I cut. You can really see how obstructed this area is, the blanket is a fiberglass blanket I put on the engine to protect it from the sparks of the cutoff wheel I was using.