New driver merging in PA

I recently moved to PA where the merge lanes are quite short. Lately I’ve seen many posts about seeing the headlights of the car in the adjacent lane in the rearview before passing. This seems sensible on a straight road, but in a short lane where it ends quickly it often doesn’t seem possible to get that kind of distance. Especially if the road is curved coming into the entrance of the highway and you can’t even see the adjacent cars in rearview. i have used just the side mirror and shoulder check after first finding the gap when driving around the curve. Any other suggestions especially from PA drivers?