Pros and cons of chassis beam construction?

I'm thinking of building an off-road caravan/camper next year (myswag type of thing). One thing I'm considering is getting some UB-14 beams bent up and using it for the drawbar, chassis rails and the rear cross member/bumper and (maybe) a front cross member.



As I see it:



Pros:

Easier maintenance

Easier cable running

Easy attachment to flanges

Easier design

Stronger (minimal joins with bent rails and joins to cross members can be "tongued" for redundancy)

One piece (height) chassis and drawbar



Cons:

Weight, compared to even 150 x 50 x 3.0mm RHS (14kg/m vs ~9kg/m)

Cost (need to also factor in $150/bend from one bend place I rang)

Size (150 x 75 is the smallest beam size. Don't really care about this with the one-piece frame/drawbar design)

Torsional rigidity (cross members make this a non-issue)



Weight is a big one, but I'm thinking if I build a heavy chassis but put composite panels and aluminium on top it will somewhat balance the weight out compared to a traditional build and possibly even give nicer towing characteristics.



I'm sure I've read discussion on this before on wwforums but a quick search didn't give me what I was looking for.



Thoughts?