I have plans of doing this also only leaving earlier in May in hopes of beating the bugs in Labrador. Probably mid May, haven't Locked that down yet and talking with 3 folks that have just gone this past year for good info.
Our plans are to drive up through Labrador and cross at Blanc-Sabion. This runs up Rt138 in Quebec to Baie-Comeau, which I know 2 really nice overnights just before you reach there and the turn north on Rt 389. A few POI's along that road that should be seen including Manic %, The impact crater and of course the mining truck. The run up Rt389 and the Trans Lab is renown for it's bugs once the weather starts to turn and stays until the snow flys again. 2 of the folks I have spoken with traveled in May and report light if no bugs. The one that traveled later June was over whelmed by them! This is the main reason we're traveling in this direction, earlier and returning through Cape Brenton.
Our run would put us at L'Anse aux Meadows first and clockwise around The Rock ending over by Gros Morne and Bonnie Bay. Another I know that toured NFLD entered and left by way of Cape Brenton has shared much info of stops to make. Piley's Island, Twillingate, Fogo Island (considered by the Flat Earth Society to be one of the corners of the earth), Terra Nova, Bonnavista, Miquelion to just name a few. My family is from Carbonear so I'd be remiss not to also mention Conception Bay! Okay and St John's..
We've been only in the region of my ancestors and really look forward to exploring 'all' of the Rock! Happy to pass along more info to ya and hope to hear more of you plans as well. I'm figuring 2 months traveling so good shot of seeing ya up there!
This is as far as I've searched out possible campsites. Lots of boondocking available!

Lower left is Rt138 in Quebec. That's the route up to Baie-Comeau. We drove Rt 138 to the archipelago in Havre-Saint-Pierre. I can now say I've driven it, but probably won't again. Much better scenic drive and camping below Baie-Comeau, besides Labrador sounds so interesting! Why not travel through since you're that far already!
Happy to share what I have and am learning. Looking forward to your plans as well.