So basically you (supercell) make a megabase on a 3x3 grid of the normal grid. Clan members could attack this base over time coming and going or attacking at the same time(damage would save). Loot should be scattered around and whoever gets it gets it. But when the base is completely destroyed loot bonuses should be given throughout the clan . Difficulty should vary on how many trophies your clan has for example 10,000-12,000 has less loot and is less difficult than 13,000-14,000.Or based on how many "megabases" you have beaten . You could make a one week time limit.
I think it would be a great way for clansmates to work together and strategize!! Please consider this as a feature