If interior detail isn't an issue, it might be better to glue a piece of styrene over the top of the hole, then plug the hole with styrene tube, and use a screw. The MT plugs will work, but don't always go in straight, and often come out again, if the screw/pin isn't cinched down tight. If it IS tight, the trucks can bind, so problems either way.
If you use the styrene, it would be just as easy to use styrene shims as washers, and they wouldn't get lost if the trucks had to be removed in the future.