On a straight you should not be doing any "weighting the foot pegs and squeezing with my legs to hold on, is it acceptable to also have to hold on tightly to the bars".Stock TCS settings/maps
I don’t know if it is just in my head or if there is something else with bike setup which prevents me from going full throttle. I am better than last year, closer to 80% max versus 65% last year. Each time I open the throttle I reach a point where it feels like the bike is fully accelerating and is going to wheelie if the throttle is opened any further. I am weighting the foot pegs and squeezing with my legs to hold on, is it acceptable to also have to hold on tightly to the bars under full throttle? Even with poor driving line I should be able to go to full throttle but I haven’t been able to go to full throttle in slick mode, only rain mode....
If you have to, you are disturbing the bike.
And the reason that you have to do that is most probably wrong body position (and/or bad seat support). Your chest and chin is not on top of the tank vs your head and shoulders are sticking up from wind screen top level, you are not behind the wind screen. So your CoG is on higher level and also drag force vector is on higher level, and that make the bike (power)wheelie more easy.
If you physically can not fit yourself behind the wind screen (your helmet is poking to it), use masking tape, mask the top end of the screen, use jig saw with metal blade (fine toothed), and shorten the screen (and fairing).
I'm tall, but shorter than you, and I'm barely fitting myself behind the screen: https://www.s1000rrforum.com/forum/track-time/231057-let-s-see-those-track-bikes-20.html#post2289442