Too many people buy a place for the wrong reason. They buy without knowing the real capability of the plane. Before buying a computer, people want to know the ins and outs of the product. Don't take the given specifications for a plane as gospel truth. The Rand KR 2 and the Volksplane ll are good examples of misdirection. Neither plane can take two ordinary persons and their gear because the plane is too narrow and the engine is underpowered.
Design is easy if you start with the basics. What I am about to tell you is fact, not fiction. Your life depends on how well you know your plane. After all, it is a long way down if you make mistakes because of ignorance. Know the weight of everything you want to put on the plane. The load includes the extra pair of undies. Everything adds weight, and very soon, you are over the load limit the plane was designed to carry. Most pilots begin by installing extra technology, thereby lessening the load they can carry.
Many pilots think the plane can take far greater loads than the specifications allow. That may be true until you start to turn the plane or run into turbulence. Then, the extra overload can and will kill you.
Before getting a plane, take out the scales and weigh everything, including winter woollies and technology, plus your first aid kit, life jackets, and water bottles. Once you know the largest load you add to the plane, you can look for one that suits your needs.
Let's talk about modifications. Planes are designed to balance on a pocket of air. The air is thin. Nothing will stop you from coming down if you are out of balance. The risk is too high to ignore. The wings, the tail group, and the engine form part of a calculated balancing process. Alter any parameter, and you affect all other parameters that make up the design process of a plane to keep it in the air.
This booklet shows design basics in a simple, explained process without technical terms you don't understand.