I guess I'm in the minority...I think allowing motorized access to the beach is critical until the road is finished/paved.
There are resort hotels and private homes situated on the beach north of the bridge. There have been many near misses of motorcycles and children on the beach.
If you were paying $350US per night plus to have a romantic or simply relaxing holiday where you could lay out on the beach - do you think it would be right to have motorcycles whizzing by between you and sea?
There are many misconceptions about who the beach belongs to - Everybody has been lax about this for so long but the problems are becoming tougher to ignore. There is no legislation preventing motorized vehicles from traveling on the beach - looks like it might be time to make some.
If you don't find the road passable then a boat would be a better option to traveling up the coast. And you will see that this is the typical mode of transportation for land owners that are north of Costa Maya.