Remember that you can't take as example short races of 5 laps and "hotlap aimed" sets:
For having some proofs of that theory you should do at least 2 3 stints of about 1 hour on 2 3 different tracks with both cars and a well developed setup. (and for having a realistic result avoid locked differential sets)
I have no experience of long BF1 races so i don't know how much tyres would last, but it can differ a lot depending on setup, track and driving style.
You should test before saying that, imho.