Effects/adjustments of using a "not-ideal spec" ski

SlalomSteve

What are the effects of using a ski that is either too big or too small for one's weight; and of using a ski that is designed for 34-36 mph, but being skied at 28-32mph?
And are there any generally-applicable adjustments (works in most situations) that one can make to mitigate any negative effects? Boot placement or fin, though personally I'm not yet making fin adjustments off of stock.

If one is on a bigger ski, the ski will sit higher in the water; smaller ski lower in the water. Slower speed, ski will sit lower in the water.
Given that, I was trying to reason out the physics of it, but I don't understand the physics of it enough. One alternate, more generalize way to ask the question could be: what are the effects on stability, speed, and turning ability of a ski sitting lower or higher in the water than it was "ideally designed" for given weight/speed, and how to remedy any issues?

lpskier

So that’s a big question. I’ll start an answer with this: It’s easier to make a big ski ski like a smaller ski than it is to make a smaller ski ski like a big ski.

Also, as a rule of thumb, ski on the biggest ski you can turn. So if you are on the cusp between a 67 and a 68, and you can turn the 68 reasonably well, go with the 68. That doesn’t mean buy a 68 if a 65 is clearly your size.