Hi,
Here's another thought. Many luthiers have a similar problem when displaying thier guitars at various trade shows like NAMM, where thousands of people will "try out" a guitar. There are clear plastic pickguards that simply stick on without any adhesive and can be removed instantly without a worry as to damage to your guitar. The only draw back is that they cannont be left on for days or they may damage your finish. The only guys i know that have them are the folks at Colling's Guitar in Austin. You can call them at 512-288-7776.
If you chose to put a permanent pickguard on your Martin, have Martin do it, the value of guitars will generally be dimished if not 100% original.
Nina