You are right about the one-way airways, I guess they added that in the meanwhile, so I stand corrected. However, there are no MEAs published for airways (at least in Europe) and you’ll still need to go through the RAD to find a suitable route.
Just adding some waypoints in Skyvector is not gonna work. I assume real world pilots use it for real world navigation, but is it an official source? For the free version I doubt that, there isn’t sufficient information available for either pre-flight planning or in-flight navigation. It is a nice tool to crosscheck your flight preparation however and suitable for flight siming of course.
You might find what appears to be a suitable route in Skyvector but when looking at the MEAs and RAD they don’t connect. You might find an airway in Skyvector for example which upon checking the RAD can only be used for certain destinations. I worked as flight ops manager before and we had pretty advanced (and expensive) software to sort through all the different rules and restrictions, automatically optimized by using directs where available etc. for the routes we were operating.
Without such a system the only other option is to take out the Jeppesen or Navblue en-route chart, together with the RAD and sort your way through the mess. When you think you have found a suitable route, first file it via the IFPS test server (can be found at NOP-eurocontrol site under “structured editor” and see what fault s come back.
I don’t know about US, but European airspace is hard to navigate and plan through.