Eighty years old, fifteen minutes to get ALS (ten for extrication plus remaining five if all goes as planned) plus time to hospital...
Oxygen, spinal precautions with care to not compromise respiratory efforts, get to hospital. Continuous reassessment. Prepare for good handoff at receiving facility.
Think, what's in the right lower chest? Depending upon how low it is, it can be diaphragm, rib, liver, bowel, kidney, lower right lobe of lung, or even insult of a spinal nerve root serving that region. DEVELOPMENT of it may just be initial shock and adrenaline wearing off, or a worsening of general condition.
What I'd want is to pull over on the way to the hospital, with a potentially worsening post-MVA 80 y/o male, to get him pain relief...yeah, uh-huh.