I just ran the Whipsaw trail in August and it was 100% AWESOME. You can easily do it in 2 days if you keep moving. We had a group of 11 vehicles from various corners of BC, we all met up and camped on Thursday night just outside of Princeton, and then around 9AM Friday we hit the trail, and by around 4PM Saturday we were out the other end. The trail is perfect for multi-day camping as there is the beautiful Wells Lake with 2 large bush campsites right in the halfway point of the trail, and then at the end of the trail there is Lodestone Lake with a BC Forestry campsite there. The trail is a nice mix of easy/moderate trail with plenty of optional harder lines for those with built-up rigs. My brother took a stock 2007 Jeep JK Unlimited and another guy took a stock 2008 Tacoma 4wd base model (no lockers) over this trail, and it was definitely pushing these stock rigs to the maximum limit of their capabilty. Everyone else in our group was running 31s to 35s and had no problems except when we went looking for trouble. So it's not "hard-core" by any means, but it's not easy-peasy either. I would recommend at minimum 29" tires, full skidplates, basic recovery and survival gear, and at least one other vehicle along if you run into trouble. If I recall correctly it is around 90km from start to finish and once you are in it, there is no way out other than back the way you came or continuing to the end. The bugs were not much of an issue (depends what you are used to though, I am from farther north so we tend to have it worse). I think the earliest you can run the trail is around the beginning of July, due to the snow taking a long time to melt, and then it would probably be pretty wet and mosquito infested til it dries up. Parts of it are close to 6000' so it starts getting snow around mid-Sept, possibly earlier even. Here are some pics for your viewing pleasure:
This is an optional hard line. He didn't make it.
Memorial Rock, which is so named because a guy driving a Samurai flipped over backwards and died. It's about 40 degrees steep.
This is the bypass to a harder obstacle called "IFS Ledge". The bypass is really tight, but if you want to take the really easy way out there's a mud pit at the bottom you can plow through and avoid body damage.