Ciao FFD,
My experience of Croatia is that it very easy and straight forward, ATC is very professional, fuel is cheap and people at the airports are friendly and helpful
Last year, after Zadar, I went for a weekend to the island of Brac with the C172. It has an international airport with customs and avgas and costs less than Split. And if you go three times in a year with the same aeroplane registration you get a free landing.
Ciao,
AE