Yeah, it didn't make sense for me to buy those extensions. They weren't long enough, and even if they were, it would have forced me to drill several large holes to route the cable. Since I had a spool of black cat5e, and tons of those micro USB cables, it made the most sense to go the DIY route. What's nice about using Cat 5e is I have additional wire pairs available for other stuff.
When I installed this, I knew ahead of time that I was going to add a door bell button, which we didn't have before. So before I routed the cable to my chosen location for the Wyze at my front door, I slipped some shrink tubing on to the cable and then just secured it without shrinking it. When I was ready to install the doorbell, I just spliced the cable near the doorbell button, joined the doorbell button wires to that point with those butt connectors, slid the shrink tubing up and hit it with the heat gun. At the other end in my basement, pulled out those two wires (really easy to find thanks to the color coding of ethernet cable) and attached two leads I had pre-soldered to a Xiaomi contact sensor. So when someone pushes the doorbell button, Alexa says "Someone is at the door" and Wyze records an additional 12 seconds of video, beyond what what captured when they walked up to my door.
I plan to use another pair at some point to power a motion sensor, since it's looking like Wyze isn't going to be able to fix their overly sensitive motion alerts that pick up every bug or snow flake that passed in front of the lens. This is a problem that I hear others complain about with even expensive cameras like Arlo. There was a request to ignore motion that lasts less than a second, but I'm not confident we're going to get that anytime soon.
You're correct about not bothering with adapters. The cost would be much greater or equal to just buying cameras that are PoE and RTSP ready. If you're having signal issues, You could switch to a mesh WiFi router if you're not already using one and then just add nodes closer to the cameras, or you could flash some routers with DD-WRT join the main WiFi and create independent APs for the Wyze. Since you're always accessing Wyze through cloud, it doesn't need to be on the main network. However, that won't be the case once RTSP is released, so in that regard, additional mesh WiFi nodes is a better solution.