#1 Choice is trim tabs. If there is any way to find room to mount them to your boat then this is the best option. I am not familiar with your swim platform, but if it is a fiberglass unit, then perhaps a 'glass shop could cut holes from the bottom of the platform (and properly reinforce them) and allow you to mount the cylinders in an acceptable location.

#2 Choice is weight in the bow. There are lots of ballast bladder units currently available for wakeboard boats and such. Granted, the primary idea is to increase stern squat for bigger wakes to jump, but one could be easily mounted in the bow of your boat. They come with thruhulls and pumps to fill them and empty them. Might be just your answer. (I would still find some way to use adjustable tabs).