Thanks for everybody's replies/help/suggestions. (Boy, will it be nice one I finish my multi rating in a couple weeks... No lack of power/climb performance with those two 180-hp's.)
Just remember, it's not the two-engine performance that is your limiting factor in a twin. It's the single-engine performance when one mill quits.
Many light twins up here are just glorified gliders and not climbing on one engine. Down there, you gotta read the numbers in the POH carefully.
Wet grass, on landing the problem is directional control and braking. Light on the brakes and be ready to get off them and roll out. Aggressive rudder if needed.
3M0 if you land at the approach end in a reasonable distance, you may not have to brake at all. It's not that short.
If you must go around, go around early. Very early.
Otherwise, look on Google Earth. There's a run out past the parking area across the road and into more grass if you can keep it straight and there aren't any humans over there.
I don't think stopping distance will be your problem if you don't fly halfway down the runway before landing. Airspeed control and a nice normal pattern.
Takeoff, it's plowing through puddles and dragging wheels through mud. Takes a lot of energy. And the puddles and bumps all trying to knock you off straight.
And needing to pick an accelerate/stop point beyond which you're going to slide off the end into bad terrain if you have to abort because you don't have enough distance to roll out to stop.
There's a lot of jokes on here about "clearing passes" down that runway, but if it looks wet, go around and look at it real good without getting distracted enough you don't climb up to clear the power lines and ridge.
There's no harm in that, just pay attention to airspeed, clean up and climb first, just like back home... then look.
Winds were low when we were all there this year. If they're generally high in the area, I would expect some wicked mechanical turbulence off of the ridges and treeline. I'd be pretty cautious if the wind in the area is high. Others might have comments if they've been there when it's windy.
I wouldn't really call that strip "backcountry". It's well maintained, and the real limits there are the surrounding terrain. It's kinda more like a little box canyon westbound than anything. Like any box canyon, it's going to ruin your day if you can't out-climb it.
Get a feel coming off of BPK how well a Vy climb is looking. Good climb rate? Plane feeling solid or mushy? Long takeoff roll, or short? Etc. You're probably good to go into that little valley if the airplane is climbing well off the pavement. Get a feel for performance to know you have an "out".
Then your best soft field technique, that first landing there until you know how the runway condition looks and feels.
If it don't look right, bail. Use that nice climb rate and get up and out.
One of the safety nets about the fly-in, is if ya feel like it ain't right, there's either a bunch of other folks sitting at BPK who agreed (ha!), or folks who'll happily come over and fly in with ya that first time.
I think we are over-describing and being a bit more cautious online since we don't know ya and can't get a feel for your sense of self-preservation. Heh.
I don't think Gaston's presents any outrageous challenges for a truly current Private Pilot. There's lots scarier places to land. But a 172 loaded, has its limitations. If you know them well, and leave yourself an "out", it's not so bad.
If your pattern visualization and skills are good, airspeed control is good, and the runway (any grass runway) isn't an unmowed bog, I think you can get in there light. Fully loaded, we saw a few folks depart that chewed up a lot of runway but did fine with slow climbs in virtually no wind, but hot, and an extremely dry runway.
I think the Turbo 210 chewed up the most. He was rolling for a loooooong time. Heavy.
Don't get anxious and pull it off just because it's bumpy. Just wait. You need the airspeed to be right. Keep enough back pressure to lift the nose wheel if it's wet.
All those days of practicing soft field techniques pay off then. How may people have even seen a soft field by the time they've gotten their ticket if they didn't fly from grass?
Windsock is way down by the West end on the South side, by the way. Right across from where the treeline edge that borders the parking area meets the runway.
Difficult to see downwind, impossible to see well on final. Another thing to keep in mind. Look for signs of movement of the trees. You'll know the general direction from seeing it at BPK.
Fatigue at the end of an XC is a factor too. See how you're feeling at BPK.
If you're on your game, you should do fine. Not trying to scare you off of the place. Just be as prepared as you can. Run the numbers on landing and takeoff distances and see what your margins are for the day's temperatures, etc. Don't guess.
I'm throwing all of this out there because I get the feeling that you're going. So, just make sure your brain is switched fully on that day, and you'll be fine.