Our fully loaded camper, means trip ready with both of us, weight was 7600 lbs. including the loaded Stowaway 2 with the swing hitch. An estimate weight of the Stowaway/hitch is about 300 lbs. which makes our trip ready van about 1250 lbs. less than GVWR of 8550 lbs. as we no longer use the Stowaway.
Without detailed, item by item comparison it would be difficult to compare your planned van with my DIY one. At the beginning of my conversion I kept weights for added components, but in time I dropped it knowing I will be OK in van’s weight. Here are weights in lbs. for some of my components:
Upholstered sofa bed - 233.05
Galley frame - 44.85
Grey water tank - 32.55
Fresh water tank with brackets - 42.30
Hot water tank - 21.30
Awning - 61.60
Electrical cabinet complete - 113.95
2 x Fullriver batteries group 31 - 144.20
Thinsulate - 30.00
Left overhead cabinet 113 in long - 63.45
Right overhead cabinet 61.5 in long - 35.57
Housed Thetford cassette toilet in 80/20 cabinet - 70.00
Aluminum framing has many options from welded frames to assembly using fasteners. One German company and Sportsmobile are using 1” square tubing with flanges, called by 80/20 a Quick Frame, for their very modular design, great solution for low weight, fast assembly using plastic fasteners but not so good for redoing. Some folks could object to plastic corner fasteners.
There is a gamut of 80/20 profiles with T-slots to match required strength from 20 – 0.79 in, 10 or 20 ~ 1 in, 30 – 1.18 in, 15 – 1.5 in and some more, so many options.
Here is an example of my complete galley frame (22.5"Dx36in.Wx34.5"H) based on heavy 15 series with drawers and floor mounts versus a cube built from 5/8” or ¾” marine plywood. Plywood options are from 62 – 105% heavier. With combination of 10 and 15 series it could be even more, so just on galley frame savings in weight could be 28 to 47 lbs., that is not negligent.
For me the choice between aluminum frame or plywood was easy, I built the first and the last conversion, didn’t have expertise with plywood/wood cabinetry nor with aluminum framing, so weight savings prevailed. Assembly was also simplified as all extrusions were cut at the factory and HDPE fronts and filler panels were CNCed.
For high volume manufacturing I would likely choose aluminum framing either welded or Quick Frame. With low cost sensitivity T-slotted combination of different profiles would be my choice. For folks objecting to visible aluminum frame it can be nicely finished with a light weight 1/4" bamboo, hardwood, veneered plywood or plastic.