JeroenHoek
(Jeroen Hoek)
12
parking=layby is fine for such short-stop pullovers outside of built-up areas. The tag was misused for street-side parking of the type parking=street_side now covers, but the description in the OP seems like the proper use of parking=layby.
Keep in mind that parking=layby is really for the small roadside stop areas/bays where drivers can rest a bit before moving on. Anything larger that has its own service roads and facilities like those you find next to freeways is more suited to highway=rest_area, where you would usually tag the parking area as parking=surface.