One of the more fun aspects of little boats is getting tossed in the drink when you mess up, or push it too hard. The boat has a definitive way of expressing itself. Don't worry about getting tossed, spend time in the experience, learn from it and keep going.
It's only water.
+1
Does the boat have positive floation ? Will it float when full of water ?
If so, then capsizing is no big deal.
This is the first thing I do when teaching friends to sail on my 16ft Invitation daysailer.
I pick a mild day for a first lesson.
I explain that I will intentionally capsize the boat and how we will go about righting it.
Once they know that capsizing a daysailer, like a wayfarer, laser 2, etc. is not a big deal, it removes one of the major fears.
Last time my buddy and I (200lbs each) were out in that boat, we got hit by a localized cell that produced some great whitecaps and borderline conditions for a boat with a sock sail fully deployed.
We dumped it a bunch of times pushing it to the edge. Laughing all the way.
I considered wrapping the sail around the mast, but my buddy was doing fine, and the conditions, with 400 pounds of humans on the boat, were manageable without the major hassle of trying to reef that way.
A nice group in a powerboat came to see if we were ok. We just had a chat with them, hauled the boat back up and kept going.
We could see the end of the cell coming across the lake, and were disappointed when the wind dropped. It made for a tiring, but fun part of the afternoon of sailing.
Brad,
Looking at the old brochures of O'day javelins, it appears they have centerboards that slide down into the trunk.
If your boat is like that, here is a tip that may work for that boat...
Run some bungie cord from the top of the centerboard/daggerboard and attach it to something forward.
On my 16ft daysailer that jams it in place so it stays wherever you put it. To adjust it up or down I just need to pull it backwards slightly and slide it up/down as needed.
Edit: ignore above... I see that your centerboard pivots instead.
Learn how to right the boat on your own, both on it's side, and fully upside down.
Go out on a mild day and intentionally dump it.
You and your wife will become much more confident if you know you can do it when required.
(My wife and I have to right the boat in different ways, since she doesn't have the strength to pull her self up on the end of the centerboard.)
Obviously WEAR A LIFE JACKET AT ALL TIMES.
If your boat doesn't float when full of water, then ignore my post.
As for raising the sail on the water... You say your sheet is too short, which is part of the problem.
Make sure the mainsheet allows the boom to full extend either side.
That way the boat's bow can move to a bit either side of the wind direction without the mainsail filling with wind.
Would it make sense to pull the sails in while in the water to prevent the boat from sailing away?
No. Doing that allows the sails to powerup/fill and the boat will sail away or capsize again.
Keep the sheets loose until on board, then pull the sails in, to power them up and start moving.