I also require good, strong coffee. If it weren't for coffee, I would tour without a stove.

I use a plastic cone with paper filters. The secret to making it strong enough with less coffee used is to grind the coffee very very fine. I buy coffee at a grocery store and use their grinder set at Turkish or Espresso. Safeway and King Sooper/City Market have this setup, as do Whole Foods. I try to plan ahead for coffee purchasing, b/c small towns rarely have bulk or whole beans and a grinder available.

I usually just buy a pound of Peets French Roast whole beans, open the bag in the store and use their grinder. The coffee from the supermarket bulk bins is inferior, but will do in a pinch or if I really want to not carry a whole pound (hilly terrain). If you pass by a Starbucks or Peets store they can grind for you as well, and will sell in smaller portions.

I use this exact setup at home as well as on tour, I think it makes the best strong coffee using the least amount of grounds.