I bought a aerial assent wakeboard tower and the site said it would fit any boat with a beam from 66-96 inches. But i couldnt get it to fit on my 88 mastercraft platinum prostar which has a 70 inch beam. any suggestions on what i should do?

I would think this depends highly on how they are installed. I've seen lots of nice Aerial setups. But, take all that with a grain of salt. I have an overpriced Roswell Wake-Air and I absolutely love it.The aerial airborne and assault towers are very bad.you can not stop the shaking.Very dangerous.The side bars easily become loose.
The DIYWAKE swoop tower is much more stable.