I am in the same position as you but fortunately the 180 day rule will not really affect me as I do not spend that amount of time in Spain.
However, as you are probably aware Brexit will have other negative impacts on all of us who own holiday homes.
The one thing that does pee me off seeing the exemptions for the UK restrictions on travel to foreign countries. As far as I can see if you own a second home for personal use only then you cannot travel from the UK to attend to emergency issues. Yet if you let or rent the property out then you are allowed to travel for activities connected with the letting of that property. No wonder some have labelled this clause the Stanley Johnson exemption
Richard