Airframe Design: Closed/Box-Wing Airfoil

Design an airframe that uses a box-wing, or other closed-wing, shape/structure, with appropriate upper, lower, and side (vertical, or upright) airfoils. Assume a maximum allowable wingspan length (total left-to-right length, including the fuselage),of 4 - 5 meters. Assume a maximum allowable airfoil sectional width (any front-to-back section) is 1.50 meters. Assume that the intended aircraft will be operated at very low elevations, and that it must be capable of reliable, precise, repeatable, highly-stable flight at 10 - 15 meters/sec. The maximum airspeed will not exceed 30 meters/sec. Assume an all-up weight of ~ 40 - 75 lbs. The design must take into account likely maximum Head, Tail, and Side-Winds of up to 5 mph; the overall design must be able to handle and operate reliably in such sustained, or gusty, winds. One design goal is to maximize, as much as possible, both horizontal airfoil's surface areas (upper and lower sections); another is, likewise, to maximize, as much as possible, both vertical/upright airfoil's surface areas (left and right). If we assume that the aircraft is to fly in calm to mild conditions only, it is NOT necessary to maximize high-stress, high-torque, high-acceleration, high-torsion withstand performance and specifications. Airframe materials, components, structures, designs, and structural-performance specifications can be relaxed greatly so as to reduce airframe weight. However, it is NOT necessary to minimize such withstand performance and specifications, and it is NOT necessary to minimize airframe weight. (Please do not spend much time on airframe weight minimization! This is not an overriding design goal!). The intended aircraft is not in any way to be a performance, sport, acrobatic, competition, or other similar 'performance,' 'sport,' or 'competition' aircraft. In-flight Stability, very-boring precision-flying, holding accurately to precise flight-plans (e.g., way points), paths, and patterns, and reliable, repeatable (boring BUT accurate and precise!) flight, at the stated speeds, and under the stated conditions, is the Key Design Goal. There is no wing shape, design, or form preference or requirement; the top and bottom horizontal surfaces can be symmetric, parallel, stacked, flat, curved, tapered, or staggered (one swept forward, the other backward). Likewise, there is no 'required' fuselage shape, form, or design. As I am not an Aerospace Engineer, Aeronautical Engineer, Airframe Designer or Engineer, Airfoil/Wing Designer, nor a Pilot, I have perhaps made a number of (serious?) mistakes, or errors, above. I may well have left out (omitted) critical, necessary--to-the-design, information, details, or specifications. If you are experienced, educated, trained, and/or knowledgeable enough to know that I have done so, please do point these things out to me immediately, so we can modify (or correct) some/all of the above description, information, details, or target 'specifications,' and continue the task/job.