Focker,
Growing up in Bozeman, and now living closer to Red Lodge, I thought I'd give you a little information about ski shops in the 3 places you'll be skiing. For Red Lodge, I highly recommend The Ski Station in the town of Red Lodge. The area rental shop does list "high performance" demo skis, but I have no idea what the brands are. In Bozeman, I can highly recommend Ph.D Ski (ask for Kevin, and let him know Simpson sent you), and Chalet Sports. They are both on Main St. with the Chalet being downtown, right across from The Baxter Hotel, and Ph.D on the west end of Main, right past a Perkins restaurant. The shop at Bridger has great brands, but it's generally busy as hell on the weekends! At Big Sky, I highly recommend Lone Mountain Sports in the Arrowhead Mall directly behind the main lodge. In fact, I'd also park in the lot that separates the two. They have all the best stuff and keep them tuned! In addition, the coldest beer and great food are located directly above the ski shop accessible by elevator! It's called Scissorbills. Lastly, the North Bowl is mostly a mogul field these days. If that's what you're after, great. If you want a chance for some softer snow, Schlasman's chair is your best bet. If so, rent a transceiver where you get your demo skis.
Have a great time!