Also try soaking the fruit in brandy/alcohol/fresh squeezed juice before the baking for a day or 2 as this gives it a head start
I always double wrap my rich fruits in greaseproof paper and then foil. Then place in a tin, and then keep in my pantry for between 3 weeks and a year. My grandmother kept hers under the bed, but she had no central heating in the house. My Mother always says NOT to wrap with the foil directly in contact with the cake. My cakes seem to taste better once left for at least 8-9 weeks. Also I Baste (feed) them at least once in that first 6 weeks.
I've never tried the cheesecloth...is it not affected by being sealed in plastic??