The goal is to keep the interior light, functional, comfortable and simple.
Several other recent -3 builders have installed the Oregon Aero seats with apparent great satisfaction. Currently that is the plan. A two part seat with a removable back rest to accommodate a backpack parachute when desired. While the original seat back is fitted and installed, the bottom is attached slightly forward of what may be ideal for my height, I may end up modifying or fabricating a new unit to better accommodate the parachute and my fit.
As the plane will be based in the sometimes cool Pacific Northwest, an electric seat heater is planned. Some level of insulation will probably also be desirable.
Side arm rests and some type of padded instrument panel visor should round out most of the remaining interior appointments.