Biohazard

You can pull the front a/c vent off fairly easily to get that cleaned and disinfected.

3 years isn't as bad as it could be. You should smell 27 year old gas, nasty stuff lol.
I would fill it up and buy a couple fuel filters. Or with as little gas that is in it pull the tank and inspect it and the sending unit. you can pull sender without spill if it has 4 or less gallons in it. Get a new fill tube grommet before doing it.