Phil, not to beat a dead horse, re the river crossings, but rather to correct my statement, "I don't know what the switch over time from ice bridge to ferry might be, would expect a few days tho."
Looking at the NT (NWT) Infrastructure website you linked, on Winter Roads page, I see the two ice crossings in question are closed May5 and 6 (15 yr avg). On the Ferries page they are both open June 2 (15 yr avg). So the "switch over time" for ice flow is quite significant - no need for you to rush !
As you'll know, there's ton's and ton's of travelling The North info online - so much so you don't really have to go, tho now of course, you've got us talking here about 2019 (!). Anyway here's one more site that I found useful for roads. Some is old but has some go pics, fwiw. Maybe not much for this trip but put it in the vault.
And my final tip - really, I'm not supposed to share this stuff - is Dredge #4, just outside of Dawson.
Enjoy !
~David
