Stability/balance?

Would it be safe to say if a paddler learned to paddle a K-1, or some other kayak or surfski that was 16" wide and 16' to 18' long (all very unstable boats/skis),in flat to choppy water that he/she would be likely be able to manage a 21' long, 17" wide surfski in more challenging conditions like mild Maui days?
The reason I pose this question is that at home I only paddle in front of my house on a pretty calm bay so I'm wondering if I get used to the tippyest of boat/ski at home might I be able to rent a more mormal, i.e. 21' X 17" ski on Maui and remain up-right in mild ocean conditions? I don't mean big surf but just open ocean swells and chop.
I'm about three weeks into my S1-X now and getting pretty comfortable on clam water. I've even survived a moderate wake or two but I'd really like to learn to be stable in the tippiest boat/ski as a personal challenge and so I'd feel even more comfortable in a 21' X 17" ski. Does any of this make sense?

Yep makes perfect sense to me.

In reality im only pretty new to this sport.
I paddle in a bay that is either dead flat.Or there is wind chop.
We don't have the ground swell coming from the deep ocean.

Similar to a river or lake when the wind blows we can get a fairly decent wind wave happening.But there is no power behind them,as the wave isn't very deep.

When I go out in the ocean I can feel the pressure under the boat.Even on rolling ocean swell the power is huge.Pushing the boat around underneath.

So can you do it?
Absolutely.

But I think it will come down to how comfortable you are in the boat as even though you may not see a wave of any significance the ski will be pushed around under you.

For my two cents worth.Keep paddling.Use your Swiss ball every day to get used to something moving underneath you.Pick your day and go out and give it a go.I think you will be fine.

I paddle a K1 and an Elite. Paddling the K1 helps with technique, more than any anything else. You can not replace what I call 'ocean feel' though taht you get with a ski.

Of interest, how much success/improvement have people had with using a swiss ball?

To be good at ocean paddling you need to paddle 3 to 4 times a week, in the ocean in all coditions.Have a boat for flat water and one for down wind paddlng.Master both conditions in 2 boats.