Personally RTI scores don't mean junk to me, especially when an RTI score makes no specific determination about proper suspension geometry.
You can run 4" spring lift with a short arm kit, on the street, you'll probably never know it. once you introduce axle articulation to the equation, this is where the issue arises, and it gets worse once you lock the axles.
I understand your on a highschool budget, so budget your money appropriately.
if you want 33" tires, get a 1" body lift and 2" Budget lift. you will be with in the useful range of the stock arms, fit the tires, and have fun for less money. then I would save up for some rocker protection, oil pan protection, front and rear lockers etc..
Just to add, in my opinion, lockers are more helpful offroad than slinky suspension