It's kind of funny I found this thread now, because about a month ago, here in Edmonton, I saw a truck fitted with one of your beds (with a little Oztray sticker ) and I looked up your website.
I think I made mention of it here on this site as well.
I like the stripped down look of the bare-bones bed as well, but I might be in the minority along with you.
I REALLY like the idea behind making it totally modular, building how you like it, adding on pieces to fit the needs of the job, or the trip.
I would like to see specs on the load carrying capacity of the upper supports. I'm thinking along the lines of putting a roof-top-tent up there (150-200 pounds) a couple of adults and 2-3 little ones also.
Thinking to safely hold the weight (and the bouncing munchkins) you'd want around 1000 pounds safe working capacity.
Wondering if you will be testing the weight limits to ensure any weight capacities are accurate?