Hey Siliconshaman LOOK I remembered to mark the edges before I took the hinges off! (for which i MOST PROFOUNDLY thank you)
ANYWAY I cut most of the first mortise with the Correct Tool, which is chisels!

But then I realized that 1) it’s not gonna be precise no matter what tools I use & also 2) I have a jigsaw, so I cut the second one with that & they’re both more-or-less the right size. Ish.

See?

I’m REALLY glad those hinges are sturdy, cos that way I avoided having to take the entire door off. I just undid each hinge, cut the mortise, & screwed the hinge back in. That said, I had a table under the door, too, to hold some of the weight.
That went quickly enough I figured I’d try getting the deadbolt on!
I’d decided against putting an actual doorknob on the side door about three point eight seconds after deciding I wanted a side door, because the chances I would run an entire doorknob sticking out of the side of the tinker’s wagon into something Large were approximately a hundred percent. Yes, I know a know only sticks out like an inch anna half past where a deadbolt sits. Yes, I shouldn’t be driving the tinker’s wagon that close to anything ANYWAY. Too bad. Deadbolt.
After a LOT of futzing around I got the thing attached!

It turns out that the door originally had a different sized doorknob! Which I didn’t know was a thing! But lo, a gap.

Which is fine, it’s on the inside, I know how I’m gonna make it neat, AFTER ESTRELLA.
Can’t lock without a strike plate!

Fortunately(?) there’s enough of a gap all round the door that I didn’t have to cut a mortise for the strike plate!

& now? It locks AND unlocks!

& yes, I DID remember to bring the keys inside when I was done.
This was posted originally to my Patreon, a little over a week ago.
If you want to see these posts sooner, & not incidentally help support me & my cats in our travels & such, the way to do that is to sign up as one of my Patrons for as little as a buck a month.
I’d REALLY like that.