Digger,

I have built alot of the .15 sized airplanes. Most were cut out by hand. One I remember in particular had 210 square inches and weighed about 2.25 pounds. That's what...about 25 oz/sq ft. No gear, just skid plates on the bottom. I'm not the best flyer around so when I say it wasn't too hard to land, that's probably like saying "It'll be no problem for you!" I'm not sure what the landing speed was, but it would only skid about 15'. I probably could have done better than that, but I never had the chance with that one. The fifth and last flight I put a 7x6 prop on it. After running an 8x4 prop and doing alot of rough flying I should have cut the control surface movement down a little. It reached well over 100mph when it started doing tricks and I was yelling "I LOST IT!!!"
Since your building a scale airplane, 42oz isn't that bad. A .15 LA will put out about 2.65 lbs static thrust. (assuming an 8x4 prop) That means your running about a 1 to 1 ratio. Combine that and the wing loading and it should fly pretty scale-like.