Oh dear, a boat 'with work'.......
Here's my experience:
My diesel (different but also smelly) tank is mounted in a way that I cannot remove it (without dismantling half te interior) to clean the surface underneath (which smells due to earlier spills)
If I understand correctly, the source of smell (gasoline) is gone (for the moment) and the smell remains. If this is true, you need to get rid of the odour. (this is relevant: if you don't remove the source, there's no next step).
find some plates (the things you put your food on) and make a nice pile of ground coffee on them, 2 to 4 plates. The coffee absorbs the smell. The boat will smell of coffee too, if you do not like coffee smell: replace interior of boat. (just kidding: after the fuel smell is gone you can ditch the coffee and it's smell will go faster than the fuel smell)
Nevertheless: remove the source of smell: so clean the 'box' where the tank was that smelled. Very, Very, Very clean. Fuel (gas or diesel) is not a friend to the human nostrills.
Close/plug any opening between tank/engine room/whatever smells and the living area. (I know, sounds stupid but with a buring sun on the boat every creak counts)
Gasoline vapourizes, the smell ventilates away. All tricks mentioned are to shorten the period of discomfort.
You may have to think of a way to ventilate the interior during the time spent at the mooring place. I've noticed that (my last century Carver (1992)) that this was not an issue at the time but it is to me: the boat in dock is heating up and has no 'natural' way for hot air to get out of the cabin. Bit of a missed chance as the fly-bridge allows for an exhaust under the cover somehow.
Combine: smelly tank area and no ventilation when it matters that the windows are closed: result = more smellyness.
Invent and realise: extract air from smelly area to outside.
Notwithstanding: take care of the source of foul smells, it will increase the effect of any measures taken...
