Gas Box Hinges?

Barefoot Wanderer

Hi, The Caravan I bought has been slightly butchered in places and I'm having some fun restoring her. At some point the previous owners decided to replace the gas box hinges with a pair of garden gate hinges - the result was two nasty rusty lines down the
front of the box.

The problem I have is now that the box is clean (almost) I have 3 holes in the front and 2 rusty hinges - Are there a "standard" hinge for gas boxes? I have a Rapido club1989. What's the best way to fill the holes with (not fussed about a perfect white-colour
match) - bearing in mind I'm doing this budget style