One way to not mine empty ones, change The min size, but a empy block brings coins...
Block creation options:
-blockminsize=<n> Set minimum block size in bytes (default: 0)
-blockmaxsize=<n> Set maximum block size in bytes (default: 750000)
-blockprioritysize=<n> Set maximum size of high-priority/low-fee transactions in bytes (default: 0)
This doesn't alter what's going on inside p2pool that mines an empty block (whatever that is). Perhaps the merged mining is the culprit... that almost certainly causes far more losses than any gains people think mining bullshit worthless coins might have. At 5-10% more reward due to transactions currently, one really should try and mine transaction containing blocks as much as possible.
funny thing is, not being familiar with command line prompts, I don't even know how to withdraw my bullshit worthless coins that were likely the reason for the low transaction fees from the block I found yesterday and the one with no fees from last night