Fine, then we're back to Skills and Feats for the Foxdragon.
Freyar said "Stealth skills would seem to make sense" which I'm inclined to agree with.
A Pseudodragon's skill ranks are Diplomacy 0, Hide 6, Listen 6, Search 6, Sense Motive 6, Spot 6, Survival 0. Those don't work out right - it should have six skills at 4 ranks, not five skills at 6 ranks.
We could give our Foxdragon the same five skills as the Pseudo 'corrected' to 5 ranks and add another skill - I'd go for Move Silently.
That'd give it:
Skills #1: Diplomacy +3, Hide +16, Listen +6, Move Silently +8* (+12 flying), Search +5, Sense Motive +6, Spot +5, Survival +1 (+3 follow tracks)
Plus any bonuses from Racial Traits, Special Abilities and Skills we decide on.
I still like the idea of a "+4 to Hide when using heat haze", which'll give it the same Hide modifier as a Pseudodragon.
Also, how about changing Search to another skill? Since they're 'Tricksy' I think Bluff would make more sense, which'd give it:
Skills #2: Bluff +6, Diplomacy +5, Hide +16, Intimidate +3, Listen +6, Move Silently +8* (+12 flying), Sense Motive +6, Sleight of Hands +5, Spot +5
I like the #2 mixture better.