I'm using a CAB1 with the Lionel LCS App - all it takes is a null modem between a SER2 and the CAB1 Base. I finally located my cache of DB9 connectors to solder up a connection wired as a null modem (pins 2 Rx and 3 Tx reversed). I'm able to operate my switching layout using the Lionel LCS App to throw switches and the CAB1 to control a TMCC loco (the Beep), accessories, and switches. A STM2 provides switch position feedback. The switches are Command controlled so no ASC2 is needed. The SER2 transmits switch throw commands to the CAB1 base which transmits the TMCC RF signal to the layout.
This is a fallback solution if my Base2 fails before the Base3 is available.