You might also want to check out the Ala Kart. AMBR in '58 & '59 It had air bags, way back then. link below, or google it for more info. http://rodcustom.automotive.com/92349/0809rc-1929-ford-roadster-pickup-ala-kart/index.html
this looks alot better than what i had originally imagined, still doesn't look right in my eyes, but looks like it would work well
I think this sums it all up. Been done? Yes. Could work properly? Yes. Traditional? No. If you are looking to do "something diffrent" then it is not traditional by definition. Like it or hate it, its not wrong or right but thats what this board is about.
I'm not a fan of air bags but,'Demented' built a very cool car. http://www.jalopyjournal.com/forum/showthread.php?t=447354
Technically, 6-8 degrees leaned back is actually positive caster, and the way you want it. I've heard of as much as 10.
If that's what you mean by "traditional" I submit that "traditional hot rod" is a contradiction in terms!