I have the Base 3 on pre order, in the meantime I just use my phone with the Lionchief app to control my legacy engines via bluetooth. I have an old iphone I just leave on the train table to use for this so I don't have to use my personal phone. Nothing fancy, apply 18 volts using my transformer to the track, then power up the phone app and connect to the engine.
Also, I have the Lionel universal (orange) remote that I use for my Lionchief Plus 2.0 engines, but that would work for Legacy engines as well.
Yes, you don't have all the legacy features, but the engines work, smoke, blow the horn / bell, crew talk.
You could just go conventional too if you wanted.