Sorry, but the DE isn't any heavier than the E, maybe by 20 lbs, so stop chewing on hamburgers or throw that big GT45 turbo outta the way, it must weight at least 20 lbs by itself!!! Ah, and a DE cost 1k$, just a little more than this stupid turbo of yours and you'll get more hp than you will really ever need in a s-12 with a STOCK vg30de. If you own a good MIG welder and can wire a car, this swap will be a lot more cost effective then trying to boost a N/A s-12 vg30e.
And the clearance problem, the only thing that will be tight, is the clearance you'll have between the struts towers and the valvecovers, it will fit, it's been done, but it'll be tight. So don't worry about oil changes, for those of you that never did this, the filter is ON the SIDE of the block, not sticking on the valve cover's side right above the exhaust. So just lift the car like EVERYBODY does and get UNDER the car, you'll have no problem.
Man JEFF I'm starting to wonder if you actually read yourself back before posting, those shit you are saying don't make any sense, even if you read it backwards....
Oh and btw a centrifugal supercharger (yes that how those are called) will require a custom bracket, custom pulley and all the above mentionned (ECU, Fuel rail, injectors, IC, piping, etc...), I do not think it's easier than welding 2 engine mount and 2 tranny mounts, or you could throw an Xterra supercharger, but you'll have to swap the crank to use the right pulley and cut the hood, that's even easier..... god!
Just my 2 cents!