Hull and slice strawberries into quarter-inch thick slices. Mix with 2 tablespoons of sugar and let stand while you prepare the cream mixture.
Whip heavy cream until stiff peaks form. Add mascarpone cheese, remaining sugar, and vanilla, and mix well to blend ingredients.
In a clear bowl with steep sides or a trifle dish, place ladyfingers on bottom and brush with rum. Add a layer of sliced strawberries. Follow with a layer of mascarpone/whipped cream mixture. Repeat with ladyfingers, rum, strawberries, and cream mixture until you reach the top of the dish, reserving about 3/4 cup of strawberries for the garnish. The top layer should be the cream mixture, and can be piped on with a pastry bag or spread smooth with a knife or spatula.
Arrange strawberry slices on top of the cream mixture in concentric circles, from the outside of the dish in, leaving a 2-3 inch border of mascarpone mixture around the edge, to create a flower design. Works best if you use the largest slices on the outer rings and smaller slices as you move towards the center of the dish. Finish by standing 4 small strawberry slices in the center like the center of a rose petal.