DCC conversion of a Tyco Plymouth CR-4 and Tyco Searchlight Car

Hi all! As stated in the title I am converting a Tyco Plymouth CR-4 to DCC. I have a fantasy Railroad that it would be perfect for. I have seen another post on here doing such a thing but they stripped the whole motor down and reworked it from the ground up. I don’t have the tools or resources to do such a thing. I am trying to do this on a bit of a budget.

I have found enough information to help me plan how to isolate the motor. My main concern I don’t have an hobby stores near me and I need a decoder but I don’t know enough to pick ther right one.

Would an N scale decoder work, and if so which one would work in a small space? I don’t have an hobby stores near me to help me with this situation unfortuately.

Also, I am looking to convert a Tyco Searchlight car and need recommendations for a decoder for that as well.