Mw,
I have fished the Potomac out of a 15' 6" 1980 Skeeter, 275 Pro XL Stratos, 285 Pro XL Stratos, Z19 Skeeter and a Tracker 16 and am not dead yet. All of these boats are less than 18 feet. A 19 foot boat is recommended if you want to jump waves on a windy day on the main river. If you pay attention to wind forecasts and conditions on the water you can fish with just about any sized boat on the Potomac. If you stick to Potomac creek, Aqua creek or Occoquan you should be fine. Just don't go out on the main river in 10MPH+ winds.

The 176XT may be a better boat for you price wise. You might want to take a look at them. I prefer the 275 with a 115. Both would work for Aquia or Potomac creek eventhough I think all of the fish have disapeared from Potomac creek:o)