So you had a smooth crossing. When I crossed the boat moved enough that I had to hold onto something, all the time.
Take a walking tour in Old Alamos. Facing the big church...to the right is a raised walkway with a long row of arches. Under the walkway are offices. Here was a nice older gentleman who lead walking tours. It was well worth the 100 pesos.
I stayed on the edge of town for about $20 US. a bit low end, but secure parking.