I am familiar with the parking woes of which you speak! Not only do I occassionally post on this site, I was fortunate to get a part-time job at the Cabela's store in KC. So, when not chasing speeders and drunks on I-29, I work at one of the coolest stores in the area. And, the discounts are kinda nice too! All my trooper buddies ask if I just sign my paycheck back over to the store. Boy wouldn't that be easy to do!!
Back to parking, try to come early in the morning (store opens at 8 am through the week) on a Monday or Tuesday. Like many other venues that draw large crowds, try to avoid them by showing up at an "off-time".
Directions to the store from Iowa via I-29: Go south to Platte City (MO) exit on I-435 (Topeka exit), continue south and cross the Missouri River into Kansas. Take the State Avenue exit and it's on your right, can't miss it! It's 42 miles south of St. Joseph, MO.
Enjoy!
MO