We went there years ago when the Dempster first opened as far as the Mackenzie River but not as far as Inuvik. We were there about Labour Day weekend and had no trouble with bugs but it was freezing at night, quite hard, although the days were absolutely gorgeous. One of my best trips ever.
The area from the Ogilvie Mountains north through as far as Eagle Plain is spectacular. Ogilvie Mountains are something else. We drove as far as the Arctic Circle one evening. The red and yellow fall colours were on the 'trees' (about 2 inches tall willow and blueberry), the air was crystal clear and from the high ground on the north side of the mountains we estimated we could easily see 100 miles in each direction.
We had tremendous Grayling fishing in the Blackstone River where it flows alongside the highway north of the Tombstone campsite but it is a small stream and I suspect by now it will be seriously depleted or the fishing is probably restricted. We did see some Grayling in the larger Ogilvie River but didn't have much luck. Other than that we didn't find any fishing in spite of having a few casts at just about every culvert and stream.
Where we did have great fishing was at Aishihik Falls west of Whitehorse, an equal quantity of Rainbow and Grayling. Aishihik Falls are the falls that used to be on the back of the Canadian $5 bill.
I always wanted to see the land farther north but never got back.
I once spent a summer at Cape Parry, about 100 miles east of Tuk. Got out fishing one day on a lake and when we found the fish they could be caught on a bare hook they were feeding so voraciously. About equal quantities of Lake Trout and Arctic Char. I should digitize my old slide pictures.