I met a couple at a rally in Norfolk once. He rode a HD Glide and she rode pillion. The bike had 93 k on the clock. He loved to do big miles; she didn't. Her technique was to fill a (very) large plastic bottle with a long straw with a 50/50 mix of vodka and coke. Other drinks are available. Within an hour she would be asleep, held in place by the glide's wraparound seat, while he enjoyed the ride. They toured Europe like this every year.
It might not be the perfect answer for everyone, but, for them, it worked.
It might not be the perfect answer for everyone, but, for them, it worked.