Provide a good mechanic to your local customers, that will keep you afloat. You won't make a living off the bikes alone. IMHO, suspension work is where it's at for an off-road shop since most enduro/hs riders pride themselves on doing their own wrenching, but most won't touch the suspension.
Have a pocket deep enough so you can have one or two demo bikes at all the local events. Let anyone and their brother ride them. Go to all the races you can possibly make it to. Have extra spark plugs in your pockets for the guys who foul at the start line.
Most important (I failed at this one at our shop) RIDE. Don't get caught up in the business/marketing end of the shop... ride and race and do it respectably. Gas Gas riders respect a dealer who is out there getting muddy and whipped by the trees with them.
Don't overlook the potential of local motorcycle shows. We entered full enduro armored Gassers in a local Harley/Custom show and always got tons of response each time. (Usually we had the only dirt bike so we stood out!) We also had a vendor booth at each show with box stock bikes to show.
Keep a well stocked parts shelf and keep up on the aftermarket parts for Gas Gas. Know the bikes like the back of your hand.
Get a good contract with a nationwide shipper so you can ship the bikes anywhere in the US for less than $400.
You're in a good location for the entire south eastern market and fairly close to Dixies warehouse as well. You could save some freight charges and go pickup parts and bikes on your own. (I'd look at Husaberg as well to have big four strokes available for guys who are tired of pumpkins)
I'd go for it. With Gas Gas you have to go get your customers. They're out there, you just need to let them know you are.