I have been worried about the same issue. In Europe bike racks have to have lights. Not here in the US. I have used these magnetic lights you can put on the trunk or roof top. Towing companies use them as well.
Some like these:
https://www.amazon.com/MaxxHaul-8077.../dp/B078GNDQQH
https://www.harborfreight.com/12v-ma...g_q=tow+lights
I put them on the top of my SUV which is higher than the top of the bikes. This way the lights are visible to traffic behind me.
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Not driving a stick but riding one.
Last edited by Harhir; 08-16-21 at 09:09 AM.