The blinds are in a trailer (park model) and do not come down. What is the simplest way to clean them while they are hanging?

Never soak them as you could make the finish bubble. Vacuum them first - running the soft vacuum attachment over each blind and making sure to open the air flow valve on your vacuum so you don't put too much pressure on the mini blinds. Then close them and Windex (I usually work with 12" at a time) then wipe each blind with a microfiber cloth. Note that you will have more dirt on the top and bottom blinds where dust collects. Also, if you have any bug residue (little black dots) that the Windex doesn't melt off, use a Magic Eraser.