Well, I've been driving in Africa several times, greek islands each year (as for the road conditions) and from my own country, I'm used to to such level of a road rage, that driving everywhere else was piece of cake from this point of view so far (haven't been driving in middle east or SE Asia though...). I do not plan on to drive after dark, at least not long distances. That'll be ilegal in DR these days anyway...
Was looking at Cayo Arena, but I'm afraid of this:
By "highways" you don't mean toll roads I guess ? I'll be paying atetntion, of course...
I have never been to the East coast in the DR but my guess is that in the DR, all toll roads are highways ( autoroute, autostrada, autopista, autobahn, motorway) . I cannot think of road rage though...that certainly is not a problem even though the big SUVs will try to lord over. I strictly referred to road condition: DR certainly is something to watch for and daytime driving is strongly recommended even on highways (unless it is a newly built road) and I say this having driven all over the world, bar Africa/Middle East. If I understood, you are new to the DR.
Re cayo arena, the day, I went, as I said, there were 5/6 people - we went rather late so it was very nice for me. Indeed the only reason I went to Punta Rucia was to get to Cayo Arena but I slept overnight in Punta Rucia. These days, with Covid, chances are very low that there is overcrowding but it is your call anyway.