A John Wayne style grab it and let's go twin...

Several years back a friend and I constructed a 100 inch BN-2. Its a symetrical fuselage with only the need to adjust the width in proportion to the height for formers.

There is a planset in MAN's catalog...check their web order form. A three piece wing was used on our's with ST-75's. .23-.25 c.i. gas is a waste on this 1800 sq inch plus plane. The important thing to remember about this plane is to keep that huge tail and horizonal stab as light as possible. The nose moment is shorter than it appears because of the large windshield.

Cockpit arrangement.
I didn't draw anything in CAD, it was enlarged with a copier and the former shape with interior side ply longerns were notched to align everything.

There is an exo-skeleton on the BN-2 to re-enforce it on the outside. Why you ask? The BN-2 was and still is a favorite hack in the 3rd world where Dorniers, Porters, & Twin Otters are too expensive. Those aircraft have large absorbing landing gear which soaks up the roughness of landing where only buffalo roam.
http://www.flusiwelt.de/BN2_IHER_1.gif
The B-N fuselages began to crack at the wing leading and trailing edge, around the rear door and windows. Instead of redesigning the landing gear... they simply doubled the skin in those areas.

Pilatus owns B-N. and still today is their only twin. The BN2 is assembled in Ireland after being bought and sold many times in many countries. I guess they figure since they are making parts for repair of inservice airframes its cheap enough to assemble a few each year .

Making a built up wing will reward you with a nice wing loading. In our case we used foam with an inner aluminum tube spar in a three piece configuration split just outside the nacelles.

Flaps are a must or your model will sustain the same stress as the full size. The wing is unusually thin requiring more runout than you would consider adequate for takeoff.