I think that's last resort. I shudder at the thought of dealing with the filler tube. I know, its not that bad, but its something I'd avoid.
I've got caught enough times with old winter fuel in summer months. I think the easiest method is to siphon. I remove the feed hose to the fuel pump. Take a few feet of 5/16 fuel hose from the metal feed line to a 5 gal fuel can, and have a second nearby.
For that car 5 gals of fresh anything will be fine. My car is little picky, I sometimes have to low RVP fuel in or it will have vapor lock issues in warm weather. Once summer fuel is available its fine.