The Airvan has a payload of about 500kg with 200L of fuel on board excluding pilot and endurance for a two hour flight, fixed/variable reserve and the little extra just in case worked in.
600L of Avgas = 432kg
600L of Avtur = 474kg
A 210/206/207 will lug that no dramas as well
BUT it's much easier getting the seats out, the freight in and the cargo nets secured in the Airvan!