I want to use a particular page wrapper, but it isn't an option
First, make sure that the Form and the Page Wrapper are in the same security category. If they ARE in the same category, but the wrapper is not showing up, check the Donation Campaign Security Category. Once all three are in the same category, all wrappers within that category should now be showing up.
For more information on how to change the security category of a Page Wrapper, please refer to this solution.