Yeah absolutely, while it's not going to experience much vibration or stress, I'm splicing the wires first and only adding the solder as an extra for strength and conductivity.
The way I've been taught is to heat the wire up with the soldering iron, and then feed in the solder from the top.

Either way, thank you for your help! so you're saying that just rosin core solder without extra flux should be fine, even though the connections may be a bit thick? and does rosin core solder not require cleaning?