We have lived here on the coast for 52 years and four Morgan's over the 34 years all used year round other than salted roads.
I have never fitted an indoor cover as I think they are a bad idea personally, just using the car is beneficial to all parties.
The most important job is to trickle 3 in 1 oil down the seams as instructed in the handbook, it's the bits you don't see that destroy the car from the inside out.
Nothing a good wash topsides and underpinnings twice a year keeps things healthy and a touch up of any proofing underneath annually helps.
When we have had a good Westerly the windows et al look like the inside of a Smiths crisp bag as widely reported on National news..