Camping in Jasper with small Motorhome

Are you interested in Jasper only, or the Icefields Parkway in general? I've pulled into the Jasper/Banff park campgrounds and found spots even late in the day, sometimes in overflow, though. Failing that, I have parked in pullouts, but I was sleeping in my SUV. But I did see a number of motorhomes doing the same thing here and there. I'm usually on the road by 6 a.m. and was surprised at how many people do it, still there as I went by in the early morn.