No, this is not possible the way you want it. The world map is till zoom level 10. The detailed maps start at level 11. This is what OsmAnd is built upon (and most other nav apps by the way).
The fact that trunks are visible is for the same reason as borders, big water masses, etc.: To give the user some overview of the continent, countries, and the "arteries" (highways/trunks) connecting the big cities.
Your wish is not only about visibility. These elements are simply not in that map at that level as they are not needed there. Why enlarge the map with items that are not visible (sbould not be visible) at that level?
If you want to do this you need to create your own worldmap, ór create your own map with the protected areas as some kind of a 2nd worldmap.
This requires much more than simply changing the topo renderer as it also requires you to change the renderingtypes.xml and use it to build your own maps.