Well. Since I had the flu this week (still not great) I figured to do something simple and not requiring much effort.
I had received the very nice Blik set of DK decals.

However, I thought it wouldn't be too handy to arrange the real decals on the wall without a plan.
So I printed this picture as large as possible on a A4 sheet:

and took some scissors:

Next, I needed to have a sheet the size of the wall. I measured the width of DK and compared it with the width of the real decal. That allowed me to calculate the right scale and thus how large the sheet needed to be. Had to tape two pieces of A4 together and fold one end back.
Then it was puzzling time. It will also depend on how I will put the machines of course. There will also be a heating radiator on this wall, but the size and shape is not decided yet.
Came up with these two "designs". The first is rather narrow and tries to get as many "levels" of girders.

Pretty easy to shift this design left or right. Main advantage is that the oil-barrel is there, I like it

These are the "left overs" with this design. There are some examples where more Mario's are put in on Blik's site, but somehow that feels wrong.

2nd option:

Tried to stick to the original as much as possible here. Put the oil-barrel in there, but I guess I wouldn't do that for real. Just leave the ladders hanging from the lower girder and that's it.
Really depends on the machines. I am thinking of putting the pinball alongside to this wall so it won't be so bad that the lower part is "empty". I also have to think about the switchboxes which are also on this wall (to the right).
I also left a bit of room on the top as there wil be the red neon installed there.
Left overs:

I wonder why they put the umbrella and purse in this set, as those are not in the girder level...
The Blick decals are so that they can be re-arranged time and time again, but I doubt I will do that a lot.
This also gives an idea what you can do with a single set. If you want more, you'll need more sets.