Not sure how the balance makes a difference for the guns on gaomi. Either avoid the guns' normal range from gaomi if making a flank landing or attack them immediately if targeting one of the nearby beaches. The best Japanese HMG at normal range attacks a floating LC at four FP, meaning that it inflicts DP on a four or less unless part of a larger FG and/or leader directed. Once a MG fires, use it for your noba target if it is near your intended beach. Noba will also hinder fire through it. Depending on location you may be able to mask MGs with palm trees. If you change VCA alot you don't have to leave a hex. If a hex is really masked, overstack a bunch of LC there. The 50mm MTRs, firing at two FP, are not grave threats. The 70mm gun is a serious danger (and if playing balance, the 75mm AA); do what you have to to avoid it.
Whatever they do the Americans are probably going to take some casualties, perhaps some serious ones (50%?). The Japanese may pull off a lucky hit with a 50mm MTR and sink a LC. Oh well. I would probably have two noba modules and two flights of aircraft to hammer the way in. Three flights of aircraft is not impossible either.
JR