Troll mode: Changing the rpm limits?

[Team Snille]

I have a 2014 DF 140. I am using it for salmon trolling in Denmark. The boat is a Merry Fisher 625. Unfortunately the troll mode only operates within 500 to 1200 rpm and when it is a little windy I often need to go up to 1400-1500 rpm to keep a speed of 2.8 knots . I have tried different propeller and when I try to solve the troll mode problem by changing propeller, then the sailing performance is getting worse. Is it possible to change the upper limit from 1200 rpm to e.g. 1500 rpm?

Martin, Team Snille, Denmark