Forgot to answer your specifics. We went up in August- not sure what it would be like earlier or later.
No significant problems with mosquitoes in August-- they were worse here in GA.Might want a bit of deet along just in case. We never needed it.
Rotary RV Park at FT St John as clean and well managed but would not open the gates to let us out until 7 AM.Also wanted $$$ for showers.
Yukon RV Park at Telsin lake was a nice way station stop overnight
As mentioned we liked Toad River the best.
Thw worst CG was at Haines Junction, Kluane RV Park mile 1586. It was marginal at best.
There is something worth seeing about every hour or 2 along the way,but I swear I saw the same pine tree for 6 days.
