I did a little searching around and I didn't find it sold anywhere.
I'd call Lippert customer support and ask them how to obtain that board or if a substitute can be used.
Lippert acquired IDS Electronics Inc. in 2014.
Lippert Components (division of LCI)
3501 County Road 6 East
Elkhart IN 46514
Email:
customerservice@lci1.com
Phone: 574-537-8900