To make an 2 rail O scale item, the manufacturer is immediately faced with the gauge dilemma.
Aim it at the 5' gauge market?
Aim it at the P87 (4' 8.5") market?
To sell to the 5' market, you must intentionally make a model that is not accurate in regards to gauge.
To sell to the P87 gauge market, you immediately limit yourself to niche sales.
Andre