FLR for cruise ship worker

I have seen one similar post to mine, but it was from 2012 so I want to make sure I'm getting current information.

My husband will be applying from leave to remain to FLR in just over a year’s time. We have been married for almost 4 years, I'm British and he is Indian. We have been talking about changing careers and working on cruise ships together. The issue that immediately comes to mind is whether this will affect his residency status and later application for citizenship. We could wait for another 4 years before changing careers (after he gets British Citizenship), but I am wondering if we need to wait that long.

Example scenario: We are both working on a UK cruise ship, sharing a cabin, with the standard cruise ship cycle of 6 months working, 2 months off. During this time we will be renting a room in a shared house in the UK, which have our other belongings and will be the registered address for our bank accounts and mobile phone bills.

If we are working together on cruise ships and are not often "in" the UK, will this affect his FLR? And if we continue to work on cruise ships for the next 5 years, will it affect the ILR and citizenship applications in the future?