Superchargers for 94 A blocks-question

Ok...  I have a 94 Dodge 2500 8800 lb 4:10 geared with the FI (port) light duty 360 v8 and its been one of the best vehicles I've ever owned (14 years now, 235000 miles almost all original... only normal maint items was ever needing replacement although I'm a real believer on frequent maint and its only gone over 3500 on an oil change twice in its life... and yea, one trans rebuild due a poorly designed return line lubed OD unit tacked on behind the venerable 727 (old style)... and yes, I often pull up to 10,000 lbs behind it...) BUT

I have temp relocated from 900 ft ASL(above sea level)in Ohio to 7500 ft ASL in Los Alamos NM... its REALLY a different truck in this thin air... and when we do buy property out here its likely even going to be even higher... 8200 to 8600 ft ASL.  

There is also a bunch of long multimile 6 to 11% grades everywhere.  At home its never had to shift below second for any grade with 10000 lbs behind it, but they were not 6+% and not over a 1/2 mile long, but here I'm not sure it would even do it in first at 11% (here) and I do not know how well that automatic's 1st and 2nd planetaries would hold up to much of it either.  Needs the torque.

Its running as its supposed to... i.e. the computer adjusted what it was supposed to adjust i.e less fuel... but thin air is thin air... took the top 25% to 30% of its torque clean off... I'd swear it!

So..what do do?  It wouldn't even think of pulling some of the stuff I have out/up here. I have 6 trailers.. ranging from 1500 to 10,000 lbs... the 27ft sailboat is 8500 lbs... its all in Ohio yet... but the time will come when I need to move it all here except the sailboat...  there's no water here for it... d_mn!.  It won't pull the 11% empty in OD at 55-60... Just not enough torque at 1950... which it always did before.

Besides buying a heavier 1 ton or 1.5 ton diesel which is really not an option right now... the question becomes how to get more air and 02 into this engine... only thing I know is either a supercharger or turbo... but I'd prefer the former... due to turbo lag

Any ideas on how to make it run to its low altitude design up here?  Or am I expecting too much?  (oh, the 10000 lb loads actually were some of its easier miles on the level... just ease it up to 60-65 in direct at 2750-2850 and cruise... for days on a couple trips... but that was on the mid-western flats... not here... got 9 mpg too, better than I expected.)  Running empty here I'm averaging 13 mpg... got 16-17 at home.

I'm not after Rs (at least not on this engine,see other post,"Trike Bit" I'm after torque.

Thanks,  Dave