How about having Spire like individual achievement requirement for tournament chests. Since the fellowship size is 25, maybe 1/25th of a chest score requirement to be reached to win the chest by an individual if the fellowship has won the chest. So that means 1600 min score to win a blueprint if...
How about increasing the active duration of attack and defence booster buildings so that their availability covers both the spire and the tournament reasonably well? May be by a day so that one still has to figure out when to place it.