Hi Incendo, nice truck, I would have loved a 1550L37 as a bases vehicle - I agree with Charlie on the GVM part - I've been looking at all sorts of weight saving from the start of my camper build, and with all my gear on board I will just squeeze in under GVM. My basic truck with semi complete camper box on was 4700kg, yours is heavier to start with being a 1550L37, but has a ton more GVM than mine. The military box is not the way to go for a camper - it is way too heavy.
Here is my weight list :
http://www.expeditionportal.com/forum/showpost.php?p=790108&postcount=77
My steel frame aluminium structure is still relatively quite heavy, but since I have two passenger seats in the back, it has to be "substantial" or the "Engineer" will not certify it. Even then, I have used thin wall members relying on structural strength of the section and lots of bracing more than just the wall thickness.
Once you start adding up all the little things - it soon adds up. I've been trying to save weight as much as possible, and have kept as far as best I can, a running spreadsheet on everything I've put into the truck - just a list of everything I have bought and the weight on the package or delivery notes, and it is surprising what it all adds up to.
For example, I have around 12kg of SIKAFlex in the truck to date. The under body sealant - 8 litres with 75% solids comes in at 6kg. The diesel stove is 8kg, the Webasto heater is 5kg. The fittings and fixtures will be heavy - my fridges and fridge slide weight 50kg's. The toilet and slide is 14kg's. When you look at things like taps, shower heads etc, valves, if you plan on a long trip in remote areas, you can't buy the lightweight plastic ones, you have to go with the good quality brass/stainless steel. My SMEV sink with taps and fittings weights in a 6kg, the shower head 3kg.
I've used weight saving materials were ever possible. The floor came in at 65kg's being a lightweight aluminium /plywood composite - a 3/4" plywood floor would have been 90kg and mine is heaps stronger but it is also about 4 times the price. I'm building my interior furniture out of a lightweight plywood composite - the whole fit-out should not be more than 100kg - and that includes the 27kg's of drawer runners and catches.
I was warned early on in the build by other people who's campers ended up exceeding their GVM, and I can't thank them enough for the warning, if I had headed on the path I was planning on, I would have ended up with an unregisterable elephant - and would have had to buy a bigger Unimog just to fit the camper.
In the words of Ian Chapman - always try to "add lightness" :smiley_drive: