The other day I got to the lake and it had 22 - 32 knots wind.
I just had my 7m Echo (2019 5m at home) so I thought I  will give it a try.

I just went a couple of meters out and decided it was a bit to much for my skill level (startet foiling this year).
I was alright with depowering, there was just not much between no power (flapping) and much power. So I tried to pull that blue line which did help a little, so maybe with better skills you can use it to get startet and let go when you want more power (maybe for jumps)

I will have to add a tube round the blue line (seen some pictures) as it is quite under tension and thin and hurts your fingers if you have to hold it over a longer period.

About changing the boom length:
As I seldom have the problem of too much wind I have only been experimenting with the boom length for lighter wind. It does feel to catch more wind with the shorter boom setting, but I haven't done any hard facts experiments.