Guys ive had an idea and would like to know if any one else has done this or if it is even at all possible.

Basically instead of routing vent lines to an outlet on the models surface under the fuse or where ever, Can you route a vent to another very small empty fuel tank inside the model which is in itself open to the atmosphere via an uncapped fitting in the bung?
Hope you understand what i mean, its basically the same idea as a fluid catch/overflow tank as used in various motorsports etc.

This way you can keep the vent/overflow inside the model, thus helping the scale appearance without any fear of mess to clean up.