Hi Farrukh!
I would let a shop do this with a spring compressor. I've heard horror stories about springs becoming unloaded at just the wrong time - could be disastrous for the inexperienced. It shouldn't cost very much - but you'll probably need an alignment (or at least an alignment check) afterward. By the way, I think this will look very nice on your wagon. Are you trying to even it out with the rear?