truth. you REALLY want rail support. but i would say a tripod isn't necessary. it helps for sure, but some pretty cool looks can be achieved with 35mm followcams or just handheld with the 35mm adapter (especially when zoomed out, as seen in my edits).
here's some inspiration. it's rollerblading but i try to apply it to skiing:
and another fantastic 35mm adapter video that i draw inspiration from: