I did mine on the car with my mig welder. I'ts a bit of a PITA and you have to have a bunch of stuff off....like I had all the struts and bars off anyway, and it was hard not to melt some of the surrounding plastic lines for the fuel tank vent system. So carefully done it is okay. Also, I don't recommend welding upside down but exhaust shops do it too...you get used to hot sparks.
Anyway, if that isn't enough incentive to pull the subframe then you're as hardheaded as I am.