Somewhere, I can't remember where, I've seen brackets that you hang on the wall plate of the frame during construction. On these brackets, you then place one or two beams, so you can walk on the beams. It essentially becomes like a footbridge or simple scaffolding. Probably dangerous, but still. The walking height is about 1-1.5 meters, so you can easily reach the roof trusses and ceiling. Does anyone know where you can find such things?