Hi Mike,
As you know I've been running A10's for a few years now and, like you, travel 1000's of miles on them to camping weekends and bike rallies. However, I've never had a problem with leaky rocker box gaskets. Maybe because I don't use them.
Ok, some guys are going to cringe at this but I use a "Bike Instant Gasket". It's a heat resistant silicon based sealant that replaces conventional gaskets. It comes in a toothpaste type tube so it can be carried in the toolbox of the bike and has many applications.
It works well for me and has done so for over 10 years now. It might be worth a try but if you do, use it sparingly and be careful near oilways.
Beezageezauk.