Some do this in 8 days

https://en.wikipedia.org/wiki/Race_Across_America

But 51 days is also fantastic!

Completely different experience though, since RAAM is a supported race, a very different kind of suffering. The Trans Am is a more comparable one (though still a race): https://en.wikipedia.org/wiki/Trans_Am_Bike_Race

Deciding whether to trade sleep for distance… Wild.

Your brother learned to read at the age of 4, but learning it at 7 1/2 is also fantastic!