Wicketanswered grow question a year ago I think it would take pretty long to fill it out with just two plants, i also wouldn't count on the stretch, sure it can be a lot but maybe not and then you got an half empty tent.
Check my diary if you want to i also grow in 80x80, but i got 4 plants. Still i had a "longer" veg time of almost 8 weeks.
I wouldn't go above 4 Plants in 80x80, maybe 3 but that it. But that is your decision, you can still get a nice result.