A bit of my experience!
I have fit a centre stand on my bike from OTR.When I lift my bike,the rear wheel hangs and the rear spring loses the bike's weight preload,making spring's preload adjustment way to easy.
So,for those who don't have a centre stand,you have to lift the bike,leaning it on the side stand and do the preloading.(I know this is the trouble way)
A friend of yours must assist you on that.
Hope I help!