Here are my ideas:
Dynamic objects:
- Wooden plank/board
- Light cuboid hay ball (sometimes used in real-life rallies, would probably add great flavor to SR)
- Heavy round hay roll
- Single wood log (very heavy, great as obstacle on the road)
Static objects:
- Large concrete cube (Generic static object, can be useful for scaling down to make generic obstacles or pillars)
- Generic kicker/ramp (very simple shape for scalability. Not intended to replace actual ramps, more intended to be placed on the side of the road, for example).
- Round concrete pillar
- Ring (similar to the pipe obstacles, but with just the ring and without the obstacle, could be used to make jumping stunts which have to go through the ring).
- Wooden fence