Fortress is a popular pre-season shred spot for the Banff/Calgary crowd, often providing great powder turns in October and even September sometimes.
I've only done one day there while the resort was open, and 4 other pre-season days there.
Basically the main issue concerns the bridge along the sketchyish access road. The government made them do some work on it (since I was last there) so it's probably improved, but I doubt the road would be plowed so you would have to ski in a few kilometers.
Once you're at the resort it's a great place to do quick and easy laps, with some of the best pow Alberta has to offer. Of course just because it is on a ski hill land, don't forget you are 100% in the backcountry now so all of the requirements must be met.
The other popular pre-season spot for Banff loc's is Parker's Ridge up HWY 93 by the Columbia Icefields.
If you want practice with your splitboard I'd suggest starting out from Sunshine Village... some great trails out to the surrounding lakes with untracked pow to shred (and usually broke in with a skin track already because it's fairly popular). It will be much cheaper, quicker, and easier than getting into Fortress. (save that for next fall