Hi Orange Whip,
145L board in 20+kn wind seems way too big.
Not sure what your weight is, but in the video you look like max. 180lb.
I weigh around the same, and in 20+kn Wind I start using my 95L Dyno board, or the 105L Fox. But never a 145L Blast which is in my view uncontrollable in such conditions.
It is for sure not the board alone, but also technique.
So, buy a 105L board (Severne Fox highly recommended for chop due to the Vee), put a 5.5 freeride/co-cam freerace sail on it.
Front foot stretched, full body tension, footstraps in outermost position and maybe the mastfoot position a cm back.
That should overall bring your legs in a quite horizontal position, and your body center of gravity quite far on the side of the board.
With your legs being horizontal instead of vertical, they can act much better as suspensionr for the chop. I.e. the movements of the board are not transferred into your body, but absorbed by the legs.
And then, as the others said, go fast, fully committed, and permanently adjust your course to the waves (for the higher ones, bear away and go with the waves. And aim more upwind for where the wave is low.
I just sailed few days ago in 25+kn wind with a 4.7 crossover sail and 95L FSW board. And I am definitely not a good surfer, still learning. Max speed was around 40 km/h. Look at 2:30 minutes in the video.
best regards
mariachi76