If the pedals are in tight it can be a job to remove them for sure, but once you get them off, as far as switching back and forth, just make sure you put some anti-seize lubricant on the spindles. They don't need to be installed very tight, because the pedaling action will tend to tighten them - as long as you use plenty of anti-seize, they should come off easily.
Do your pedals have an 8 mm Allen on the end? If so, you can put a breaker bar on your socket for extra leverage (because drive handles are sized according to torque, breaker bars use 1/2" drive, so you may need a 1/2"-to-3/8" drive adapter if your socket is 3/8" as it probably is if you bought a set). If your pedals install and remove only with the 15 mm flats on the outside of the crank, is there room between the crank and the pedal to get a real, longer 15 mm wrench in there, rather than a skinny pedal wrench?
Speed comes from what you put behind you. - Judi Ketteler