uk rules for lengthening body

[vortexwizard]

Hello there i am considering fitting a luton body to a chassis cab/ pickup and was wondering what the rules were on extending the body past the manufactured length? I vaguely remember someone saying 60% of wheel base behind rear wheel but cant find the thread that has this info.
Also i am not too familiar with how standard lutons are fitted and how they deal with the torsion of the chassis when a livein interior has been fitted which would presumably stiffen up the box and allow less movement. I have seen examples like this http://www.hackneys.com/mitsu/index-pivot-frame.htm where a second chassis was mounted above the origional with pivots and like the idea but was wondering how viable it would be to have the front fixed to the cab to allow a crawl/walk through and the back end pivoting to allow chassis flex.
The base vehicle will likely be a merc 308/410, currently i have a 308 panel van previously converted to a pretty standard/spartan camper but it was fitted for weekends away rather than full timing (it even has a tv ariel socket ). A luton body seems like the next step as it would give me more room, be potentially transferable to another base vehicle if needed and know several people who live in the quite comfortably day in day out. Reading the 814/815 vario projects on here and seeing this on ebay has got me wondering http://www.ebay.co.uk/itm/121366351411?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 .......unfortunately funds/age stop me from driving over 3.5tonnes which is why im looking at the 308/410 size vehicles.
Anyway slightly wondered off original question but its getting late and my mind is wondering.....

 

[ianc]

If you want to extend Merc then they (Merc) publish details on what's possible for each chassis on https://bb-portal.mercedes-benz.com/portal/ar_lkw.html?&no_cache=1&L=en
Normally you can lengthen both the wheelbase and the rear overhang. But you have to go though an approval process if you go longer than the longest size the van is available in.
Not sure of the process. I don't think 60% of the wheelbase is still the law- but it's a good rule of thumb maximum.

In terms of mounting. Have a look how I did it on http://www.expeditionportal.com/forum/threads/78237-Pre-birth-of-a-camper-No-laughing!

 

[vortexwizard]

hi thanks for the info, ive had trouble finding info on the bb portal as the t1 range seems to be missing and in its place is t2/vario info, no replys from the customer services either.
I went ahead and bought the 410 after getting the price down to 2 1/2 and one of my next plans is to raise the rear suspension as the trailing arms the air pillows sit on leave very little ground clearance. Waiting for the sale of the tail lift so i can buy the luton body, picked up a load of 50mm celotex down in plymouth for less than half trade price which will hopefully be enough to keep me warm this winter.