The air ride is going to be about 10 times more than just a progressive spring. The spring alone is about 80 plus shipping. I think I got mine from Pacific Coast Star in Ca.
The spring will do the trick if you are anywhere below what I have fully loaded. I weigh in at 250 GF half that much. I have a trunk and a Fairing and always carry 20 lbs of tools and 10 lbs gear.
Stock spring is hard, Progressive is less hard at the start but gets harder than stock as it is compressed and this is what keep it from a bottom out especially two up as it can handle more weight. Think of it like this.
Stock shock 3 rubber bands all hooked on two posts 3" apart. (single rate) All bumps one rate.
Progressive spring 3 rubber bands One hooked at 3" 2nd one hooked at 2" and a third at 1.5" Small bumps one rubber band at full stretch, Med Bump Two rubber bands handling the load and large dips all three kicking in, one at a time smoothly with greater capacity than stock.
If you were an auto mechanic you can do it. I found removal of the lower rear fender pan towards the front (4 10
mm Bolts on mine) makes it easier. It does come out the bottom, no you don't have to take rear tire off, Yes it can be a bear.
Be sure to pay attention to what other have said here about the flip, I'd say you would want to return to stock upon installation of the progressive spring if it has been flipped as that spring lowers the bike 1" in rear.
Also the links could have been changed, measure and make sure they match stock length. I think most aftermarket ones will be adjustable and have more than one hole on one end. Stock will have one hole on each end.
Mark your parts before you take it apart so you know what goes where as it's sort of a puzzle to get it out and everything will have been twisted and turned. Besides the flip. it only goes in one way.
Takes 45 min 1st time 15 min each time after LOL.
If you do a search here on progressive spring you will find tons of reading and experiences you can learn from.