It's not the most difficult thing, but it's a bit complicated to explain (and the best place to put it is probably not the Jetpunk comments section). If you want to contact me outside of Jetpunk via Discord, Reddit or email (jllarson2005@gmail.com), I'd be happy to give you an SVG walkthrough or answer any questions you may have. :)
Cringe, how do you normally make these kinds of maps? Because I usually screenshot the area on Google Maps and trace it in Inkscape - but it takes forever to do. Is there a quicker way?