If you have a fixed bimini
then boom obviously needs to clear it (and your head). This would mean dropping the gooseneck and raising the rear end of the boom. Raise it too high and you won't be able to reach the reefing points on the rear of the boom without a ladder. I think Lagoon
thought of all this when they designed it. Make a diagram to see what the end result is when you lower the gooseneck say 1ft does the boom end rise 1 foot or maybe more? - will depend on the angle required to clear the front of the bimini
. Also get the sail maker to confirm sail area differences.