Give the primary fermentation plenty of time to finish.
Cold crash the CRAP out of the beer in the primary.
Rack the cold beer from primary on top of the fruit in secondary, taking every precaution to keep as much yeast as possible out of the secondary.
Keep the secondary COLD. Very cold.
After a week, rack to keg, and keep the keg chilled (force carb, of course).
That should reduce secondary fermentation of the fruit and any "wine" off flavors.