I'd go ahead and test for Splash as well, now that you can!
He is very , very pretty, like him a lot.
The Appy may come out as he gets older- I have a Silver Bay base stallion, who I described as a Silver Bay Pinto until two years ago when he threw an Appy foal!
So, now he is a Silver Bay Varnish Pintaloosa!
It is only obvious in summer, so there is plenty of time for your boy to get characteristics.