Shane,
I'm a big guy as well…6 feet tall and around 275 pounds. Sadly, I'm not in good shape, but yes – you can hit the 20 pound mark. I also live in PA (near Lancaster) and for trips from March – November I'm at around 20 pounds starting weight for a weekend trip – and that includes food and water.
When I first returned to backpacking after a 30-year hiatus I'm sure my pack weighed at least 60 pounds. Here are some of the highlights of what I carried on a June trip where the temperatures were a high in the 90's and lows in the 70's:
– Pack: ArcTeryx Bora 80 (8 pounds empty)
– Tent: Mountain Hardware PCT2 (6 pounds with groundsheet)
– Sleeping Bag: Sierra Designs Sandman 15-degree (4+ pounds)
– Water: 4 liters to start (9 pounds on a trail that crosses good water every 2 miles)
– Fuel: 1.5 QUARTS for my whitegas stove on a summer weekend trip
– Hammock & Tarp: Another 3 pounds so I could lounge a bit (this was in addition to my tent)
Clothing? I had a complete change of clothing for each of the three nights we were planning to be on the trail plus another full set of "just in case" clothes. I carried my Crocs (1 pound) as camp shoes. My raingear at the time weighed more than 3 pounds.
Looking back at it now I realize how little I knew, but I certainly couldn't see it at the time. Mike Clelland! gave me the best tip: Weigh everything. That's where you need to start because it gives you a reference point to see where you can get the most bang for your buck.
I've purchased a lot of gear in the past 7 years in an effort to lighten my load. I've made some good decisions and some rather poor ones. You can learn a lot from looking at the BPL forums.
Shoot me a PM if you're looking for PA trails to hike to test your setup. I have a bunch of suggestions.