To me your tibias look quite tall so i would definately length femur in your case. Also your legs look already quite long, so in your case I would do max 4-5cm. 185cm is definately enough where ever you go and also doesn't mess your proportions. Also you have quite skinny body type (also yes your still young), so at 187cm you would maybe look little bit too skinny. But just maybe, not sure obviously. Also risks increase at every cm.
180cm in not tall, its average. Especially among young people (19-29), but remember its NOT short either. But if you are willing to take the risk and can get enough money for Stryde, then just do it.
Also good to remember, when i see someone my height (178-179cm) that person usually looks a little bit longer than me. It feels like when im watching that persons to eyes im watching little bit upward. Might be personal but I thing quite common "problem". Its easy to test, go to stand next to wall and mark your eyes place. Then go stand away and watch that mark. Does it feel you look little bit higher? To me always yes. I have also noticed that 2-3cm shorter person easily can see other one taller, but for example to me 176-177cm person looks exactly my height. My friend is 180cm and he has many times asked my height, because to his eyes i look exactly same height.