Dooglus thanks again for the reply, I will cut a lot mine in order to be brief. The presence of a big and slow digger seems to give headaches to a lot of CLAM holders.
What about capping/limiting the amount of CLAMs which can be digged daily (example: no more than 200 CLAMS per day)? The available limits can be given randomly to diggers who wants them. In this way we are still 'fair' towards prospective diggers and at the same time we give a 'time advantage' to current holders which are, of course, more important than future unknown ones.
It is possible to make the client counting the amount of CLAMS digged in the past 24 hours. If it exceeds certain limit then trigger DoS in mempool to reject newer digs, or give the diggers an option to proceed with a significantly higher tx fee.