For or a screw driver, find one that has a pointier tip, these stock screws are weird, they're deep but not that large of diameter. Find one that fits it perfect, not just good. That might solve all the issues. when I tried to loosen my screws the first one I buttered to all hell. You really have to push straight down onto the screws. I mean I had my leg wrapped around the ski(while it was on the lift) and pushed with one hand and tried to turn with the other. Regardless I buttered two. One I got out with a set of needle nose vise grips, I managed to turn it ever so slightly.
The screws are probably JIS (Japanese Industrial Standard) Phillips. Suzuki loves them.
Amazon and Ebay offer a couple of different brands. Though I have found that Snap-On phillips screwdrivers usually to a pretty good job of taking them out. But at the end of the day allen head screws are way better.