I've found that the 14.2 doesn't handle well at all without the jib. Too much weather helm and won't come about worth a darn.
With a jib it's a blast too sail in 12 to 15 kts. Just make sure to put a sleeve around the base of the mast to cover the cleats and such. The last thing you want is to foul the lazy sheet and backwind the jib during a tack. Also precleat the (next to be working) sheet so when you come about the jib doesn't flap the sheet as to not be able to grab it.
The other is to not sheet too tight. I've had the mainsheet all the way out, boom in the water and standing! on the barneypost needing to sheet out the jib to come back up (but not daring to go low).
Fortunately the gust passed and she came back up.
And finally, rig a trapeze type rope ladder (just one step) with a piece of PVC to hang off the back of the boat so you can get back in after you do capsize.
View it as the jib is in front of the centerboard whereas the mainsail is behind it.
This balances out the pressures (in front of and behind the CB) and allows a balanced near neutral helm.
Consider the jib as part of an airfoil system as it also creates a good airflow (slot) across the top of the wing / mainsail like a leading edge slat on an airplane wing.
15 knots can be quite fun. If you see those conditions a lot as a single handed sailor, you might want to pursue reef points.
My father was big on a two-stage tack. Meaning you stall mid-way through your tack... to give you time to climb high side. If your winds are steady (non-shifting), you can do this comfortably...
I am not recommending stopping mind you, only fast to head wind, and then slow to fall off...
If you aren't racing then lightning tacks aren't necessary (and you aren't racing since you are single handing).
I have had a blast sailing in 12-15 knot winds with the Capri. The mainsail is just pathetic without the jib. However, my main has a reef point, and you are good to about 20 knots of wind with it (although it is MUCH easier with a crewmate). Several older posts refer to places that will put reef points into your mainsail... Not something you'd likely do on a racing main, but a day sailing rig, it isn't a bad idea.
We sail these mountain lakes, and the winds vary greatly from place to place (and direction), and as my father used to say... REEF for the PUFFs. Makes for a much drier sailing experience. Unless you are into the see-sawing of riding the puffs (that can be fun too).