I don't know if you have the Sammy yet, but
take a look at project RockStar, the finished
results are on this months cover of ZW Online
main page.
I know there is a lot of cutting on RockStar, but
you wouldn't have to go that extreem, and the
buildup does a basic outline of what was done,
as well as the parts used.
I guess by your post you have all the tools and
knowhow to do a long wheelbase stretch, like
welders, torch, saws etc.
Good Luck
Wild