You can take a look at an LC filter sold here on HK as that will help reduce noise in your FPV setup. Depending on what model filter you get, it may interfere with your OSD so you may want to get one that HK does not offer here yet. that way you can bridge the connection and change it to work for your OSD.
"It is now possible to select between common mode and differential mode filtering. A solder jumper pad on the input side disables filtering on the negative/ground-lead. If you experience issue with OSD systems, try changing the filter to differential mode."
I am researching the same thing now!