Hey Mike, a KEY piece of advice.....if the skin shrinks while glued and drying and it deforms, it was not adhering properly anyway in that spot. You can rehydrate the shrunken part of the skin by applying a paper towel folded and soaked in warm water to the particular area. When rehydrated it will stretch again, then use a super glue type adhesive while the skin is still damp to reapply the area properly.
Been there done that many times buddy. I've done more skin applications than you can count.
Different skins have different oil content and there is no generic answer to if a skin will adhere to ANYTHING, never mind paint. So no guarentees, but you will learn from every application. Remember, paint has to fully cure, not just dry. So it may be dry to the touch in a day, but you cant properly wet sand it to a gloss finish for weeks. The same can be true for gluing over it. All depends which finish, which glue, humidity, oils present, temperature, etc.
Dont be discouraged by this, have fun with it. Just dont use your "Jungle carpet python skins" or "african gaboon viper" for your experiment....use a prairie rattler that is easy and cheap to replace if it botches up. Save the really good, rare skins for the simplest applications.
After most scales are off from masking tape, a pencil eraser takes the stragglers off real quick. Thin skins like copperheads can be damaged by masking tape, so go easy! Thicker scaled snakes are more leather like and can indeed be top skin scratched leaving a rough looking finish, milky looking when dry and finished over. You cant rush a skin application, everything has to cure under good conditions.
Love to see pics when done!