I use the drawer liner all the time as a sanding surface between the TS top and project. Works perfectly. The cookies also work well and I have the same issues with a pile of "stuff" making for a clear area to sand in rare. Going vertical above the fray with the cookies is one great use.
With the kit you have, the finish pyramids are also handy. Do the inside of whatever (part that will not be seen), flip even when wet and finish the presentation side then let dry. No waiting!