I use a 11.5" 400 Micron Stainless Corny Keg Dry Hop Filter. I just tie a piece of plain dental floss to the top of the filter lid and secure the floss to the underside of the lid, the well for the purge valve, with a small stainless steel hose clamp.
I do not recommend routing the floss over/under the lid seal to the outside of the keg. Doing this resulted in poor seals, with and without keg lube.
https://utahbiodieselsupply.com/brewingfilters.php#cornydryhopperI have two of these filters and don't over fill either one. A few ounces of hops expand like a mother trucker, and I suspect, lead to inefficient extraction if not agitated and allowed to expand/compress.
The hops stay in the keg for the duration unless I need the filter for something else. Not a heavy consumer, I have left the hops in the keg for 4+ months with no vegetal off-flavors (to my pallet).