All batteries degrade over time, that is a fact of life.
The batteries are there to do a job, if a disaster happens you need your bilge pumps to work
overnight while waiting for the sun to rise.
At 13.5V you will be at around 90% capacity and very little plating degradation will occur, even better if you are on solar which is cycling rather than shore power
with no rest from charging.
At 13.2 (3.3v/cell) you will be at 40% which is preferable, but you must be sure that you have sufficient capacity to deal with disaster should it happen.
In my case I prefer the safety
margin over the very marginal benefit.
In the end the choice is yours.