Good evening @Roddy4
I take it you have financial records?
And do or have an accountant do your accounts?
That may be an option as to the rental details.
Remember there's always 'grey areas' in Law that one can use.
Good on you for respecting the Privacy of your Guests.
Look under ABB 'news' & in general on Google as there's often useful info on there.
If you use related keywords in the search box here in CC you may find others who have the same issues.
There's a few Scots who contribute to the CC who you may like to send a PM to if need be.
Throw the Council a few curve balls to get them thinking outside of the square if they really need to pry into your business that is otherwise private financial matter between you & the Tax Department!
All the Best
Central To All Home & Location