FSX dispensation you say - the VA official "I used to be called President" line for FSX users (being one myself) is this:
* for VFA Tours, pilots are permitted to substitute an equivalent performance aircraft for any of the VFA fleet - FSX has the C182 and Baron 58, and there are any number of payware small SEP/DEPs out there (
FSD International) to satiate the requirements of all our small plane tours. I'm particularly fond of the FSD C337 as a B58/Seneca equivalent.
* for IFR tours, you should be good with FSX default aircraft at most classes, but again there are plenty of payware aircraft out there.
* in all cases, indicate the aircraft used at the top of the pilot notes, and what aircraft you were using it in place of. Since the VFA fleet has never had a real "identity" insofar as painting goes, don't let the fact you're not using the VFA paint scheme on your chosen bird bother you.