Poor access to engine components is not uncommon in boats. I was a marine technician for 25 years. I have seen difficult access in many boat manufactures productions. Fluid Motion is not the only manufacture that builds a boat with poor access to engine components. One of the first things I did when I purchased my C26 was make sure I could get to the raw water pump, Belts, coolers, hoses, filters, antifreeze reservoir, alternator and starter for easy access. Well access !!! There is no such thing as easy access in a Ranger or Cutwater. I was able to move stuff around and make a quick removal step in the cave to help ease the accessibility. I advise anyone that owns a Ranger or Cutwater to do this. Even if you are not a DIY owner. It will save you money in the long run. I have talked to several technicians that will not work on a Ranger or Cutwater. I have also talked to a few that will but the service is TIME and MATERIAL. The two engine parts that I could not get good access to is the electric fuel pump and starter. If one of theses components failed I would pull the engine to replace. It would be quicker to do that then remove with the engine in the boat.
Your Alternator and belts adjustments should be accessible. Spend the time to make it. It will be worth the efforts!