Being average weight a 5 m2 starts to get too much around 20 knots, but easily possible.
But weight doesn't matter, it is the spacing you ask about.
If you use and like a tad longer lines, say 25-27 meters on the 5, it minimises the gap a lot, and smoothens in a good way so lulls or gusts are no problem.
And if you like short lines, a 6 with shorter lines could be the alternative to go with your 8 m2.
Peter