I can't tell you how many times I've struggled to get a solid solder splice between two wires when I was unable to support both ends. It even works if you don't have or don't want to use solder. Like almost everything genius once you see it it's so obvious that you feel like an idiot that you missed it, at least I did.
Good stuff! Couple things: The heat shrink tubing with glue is absolutely needed, it prevents corrosion and other nasty things from happening to your electronics that electrical tape cannot. Crimp splices with the heat shrink built in are actually superior to soldering, and take way less time to do. These can be found at Harbor freight tools, Napa auto parts, most good auto/sterio supply stores, and on line retailers. A better method for soldering is to slide the two wires together so that the strands are interwoven, then you can tie them or,...... Make sure to use Electrical Solder, not plumbers, or radiator repair solder, you want the Silver content high and no acid core or even flux core, you want solid!
Cool. Ya'll seen these solder connectors with built in heat shrink ? They work GREAT for wire connections. Stick the wires in each end, hit it with a fireplace lighter (propane torch is too much, melts the whole thing easy if you're not real careful), one of those "wind proof" models that puts out a small torch like flame. https://www.amazon.com/dp/B083LZS69N/?tag=survivalmonke-20
I have became a huge fan of liquid tape to cover those connectors up as a extra layer of security against the encroaching forces of moisture!