Mick, It seems you use quite a few sets of strings. You may find mail-order is the way to go and order in bulk. Elderly Instruments at elderly.com has been helpful to me. Bring out the drool cups before you go there, they have everything your little acoustic music heart may desire.

The early Martin guitars have relatively small bridge support. With years of medium strings the top may bow and the bridge may rise up. Many luthiers, therefore, recommend that we old Martin owners (the Martins are old, not the owners, well not all of the owners) string our guitars with light strings. I have done so for many years. In my youth, I once (maybe more than once) put heavy gauge strings on my Martin. What a sound! I've had the guitar 35 years or so and have had the bridge redone because it started to move.

I play a mix of fingerpicking and flat picking and I occasionally whale away and I have been happy with light gauge strings. My Martin projects very well, it is a loud guitar.

Of course, you could easily amplify your instrument if you wish. Elderly Instuments has many devices in their catalog. Some require no modification of the guitar and can be effective, especially if you choose loudness over acoustic tone.

I use D'Addario Phosphor Bronze Lights. They hold tune very well and I haven't broken one yet.

Roger in Baltimore