Martin - If the fiberglass is that thin, you may want to put a backing on the inside. I have found fiberglass fabric to be hard to handle when coated with resin, so, if you clean the inside with some acetone, paint
it with resin and then apply dry fabric intothe resin with a dry brush it will probably stick. If it seems to not want to stick, use some contact paper over the fabric and let it dry. The contact paper peels off and then you can apply another coat of resin (and put plastic down to catch the drips.) and glue your liner back in place.
If you want to put resin on the top, clean the area and apply resin to the exposed fiberglass. Use some wide packing tape to put over the patch to keep it from running and keep bugs n stuff out. When it is dry and you take the tape off, you can wet sand the area and use bondo to fill in nicks and pinholes. Paint
it with something good like rustoleum primer and try to match the rst of the paint
. Let it dry, and wax. (The tape thing works well with small dings on the sides too because it allows you to keep the resin in the little holes w/o running down the side of the egg.):zz