There have been some previous threads about this type of crack, you may find some helpful advise in the knowledge base section. This type of crack seems to be fairly common and will likely happen to every wooden rudder eventually. It looks like you could open the crack a bit and get some epoxy in there and clamp it and put those screws back in, I would think would hold it pretty well. Mine did the same thing last season, but it split all the way down in 2 pieces. being a woodworker hobbyist I used a bisquit cutter and placed bisquits every few inches and glued it back together.
You are on the right track, you could drill holes from the leading edge, above and below the bolt hole. No bigger than 1/3 of the thickness of the rudder. Inject epoxy into the crack and into the hole, and then put in a screw or a dowel and pull the board back together. Don't go too tight or you squeeze out all of the epoxy.
The tiller bolt hole looks enlarged, you might drill it out, dowel it and redrill the hole.
Anybody ever heard of "Borer Bees"? It appears they bored a 1/4" by 2" hole down thru the tiller handle where the extension meets at the pivot hole!
While re-finishing the rudder assembly the tiller let loose while hanging by the pivot hole to dry.
I am now 2"+/- short on the tiller arm.
Oh well, still seems like the best $40 I ever spent.
The crack in mine was not as severe but I did the same repair last spring. I drilled holes and glued wooden dowels. I sailed in heavy wind several times last summer and had no problem with the crack expanding. Here's a birds eye look at the edge of my rudder.
I did the same basic repair a while ago - I fixed several daggerboards and rudders at the same time . West Systems epoxy, mixed with some thickeners and/or sawdust fills any over-rounded holes, and you can then re-drill the hole to the correct size.
to repair the splits, I drilled a hole, inserted a threaded rod & epoxy and sealed it all back up. (the picture below is from my Super Porpoise rudder, but the same concept applies)