Hi Chip
Romania was pretty crowded with Luftwaffe units either because of the oil fields or later because of the retreat.
What Bf 109 G do you have?
Depending on the time frame you can have much choices or few .... also as hkshooter wrote you could build an Romanian Messerschmitt ... before or after changing the sides.
if you have a unit and time frame in your decal instructions you could have a look here:
http://www.ww2.dk/ -->air units -->single engined fighter units -->choose your Geschwader -->look for airfields
As an Example:
JG 52 scroll down for the different groups (Mamaia, Zilistea ... many Romanian air fields here)
HTH
cheers
Steffen