I am a huge proponent of increased public transit (I'm of the opinion that every city should have a massive congestion tax with large swaths only accessible on foot or by public transit), but trains and buses would be wildly inconvenient for what op is describing.

Trying to take something like a windsurf board on a train, and then having to navigate multiple train changes along with whatever other baggage you have makes it a non-starter.

The "last mile problem" you mention is unresolved when it comes to getting from the closest public transit stop to the actual destination (frequently in a park or even off road).

And finally, the final cost to the rider would be significantly higher, as sleeper trains are not cheap.

I think America could do quite well if it focused on public transit in and between densely populated areas. Fewer cars in cities could make for denser cities, which in turn could allow for even more public transit. But outside of population centers, America is much more spread out than Europe, meaning that trains are less economical, and often wouldn't get the ridership that would allow them to make sense.