Not of the mind set to build my own PCB's, but came across this from one of the references above. It's a Boost Buck DC adjustable step up down Converter XL6009 Module Voltage, on Amazon, 2 for $11.59 w/shipping. Would this be basically a plug & play - run some wire connect to LED strip and maybe add a resistor on the IN + side?
A better choice, if I do say so myself, is the LED Lighting Regulator. This provides track power input compatibility, DCS protection, flicker-free operation, and adjustable intensity. The footprint is only 14mm x 28mm, I typically mount them on the ceiling of most cars with DS foam tape. This board was purpose-built for passenger car LED lighting for AC powered model trains. Note that you can fold the tab of the regulator over the capacitor to minimize the height of the module.
The Amazon product you mention needs a bridge rectifier to convert track voltage from AC to DC, and also the 22uh choke if you're running DCS. It's also much larger at 48mm x 24mm, about four times the size of my module. When you add the bridge rectifier and 22uh choke, there's more wiring involved as well.