Solder is preferred if done correctly, but what really matters is how well the connection will hold together and how weatherproof they are.
FWIW my electrical work on my truck is crimped, e-taped, wire-loomed, and then the wire loom is e-taped. And I spent a lot of time on the e-taping, it is a full seal.
I'm confident the wiring is solid and will never be a problem. However, if I'd had the option to solder, I would've done that as well.
Point is: Whatever you do, do it well, and it will be fine.