I self installed the window covering snaps on Journey On. And you're right, King only supplies the snaps. Here's a few thoughts:
Those pliers are great. I bought mine from Defenders, and they're sturdier than Joe's set. HOWEVER, if the snap is too far in from the edge, there's not enough room for the material, so also get the anvil type.
Put the front window covering on the inside. I can't understand putting it on the outside, but that's what King cuts them for. This is where I learned about my comment, above.
To install the male side of the snaps, I removed the hold down screws from the window edging as needed (on the inside.) I used longer SS sheet metal screws, which fit right inside the fastener. HOWEVER, that just jammed them up against the edge of the sill, so I went down to the local bolt supply house and got nylon standoffs which slipped over still longer screw and held the male snap off the window sill edge. Washers give the bearing surface needed. You could make those standoffs from metal tubing, but buying them sure saved time. As a result of all this, I didn't need to drill any more holes in the cabin's side.
Came out great, Judy's happy and I was justly rewarded.
Boris