Try the LW Beta 5.2, it does have a size filter & other filters .. some of the old ones from LW 4. If you are a pro user you can obtain the Pro beta from a link on right side of your pro page. If you are using LW Basic, get the LW beta here LimeWire 5.2.5 (Beta) - Lime Wire

A size filter was the very first thing I requested when I came onto this forum. Finally after 5 years they have implemented one. But my main purpose for the size filter was not to fight spam however it can help to remove spam from search results.

BTW Phex has had a size filter for many years.

So you tried the losing of ultrapeers technique. Great, so should work well for you.