You really don't need back purge unless your welds are growing stainless "christmas trees" out of the unshielded side of the work. It's useful for exhaust systems with butt welds and certain tubing work, but for the home shop shouldn't really be a big focus. Add an extra 5 CFH to the argon flow and use a larger cup if you really need it. I love working with stainless, the nickel really flows nicely. It also works well in FCAW-G mode, benefitting from the extra gas of the solid flux.
Regardless of the subtleties of your filler metal distribution, the fishing poles will surely stay onboard, and the fish shall surely be slain and served with Hawaiian rice.