I suggest hosting an inter-clan online tournament.

For a long time now, a semi-official/semi-online arena has been considered a viable option.
This involves giving players 15 or 22 days to complete a map offline. The player gathers the maximum number of troops they can buy, along with all artifacts (and even mini-artifacts for spellcasters), and a fully leveled-up hero, and then enters the arena for an online duel.