Indoor winter storage question

[DaveNW]

My Boxster lives in my closed, dry, unheated garage, ready for driving when Pacific Northwest weather permits. I have a Battery Tender attached to keep it charged. Gas, oil, and fluids are full. Top is up, and tires are properly inflated. It seems happy there, and has never given me any trouble. Winter here (halfway between Seattle and the Canadian Border) has quite variable weather, and we get those periodic Fall and Winter clear days when an open top drive is exhilarating.

Wondering if I should be doing anything special to keep it in the best condition while waiting for Spring, when it will start getting more regular use. Those of you with more experience - what can you tell me? Your experienced advice is important to me. Is there anything I'm not doing that I should?

Dave