jdbc-4.1 v42.0.0 - set client_encoding

jdbc-4.1 v42.0.0

Our database enoding is "SQL_ASCII". JDBC's client_encoding is "UTF-8"
We're making the leap from pg9.2 to 9.6... and existing code has started
throwing exceptions:

"invalid byte sequence for encoding "UTF8"..."

Per this thread:
https://www.postgresql.org/message-id/55CA237A.4080300@nqadmin.com

"9.4 is intentionally less lax about that than prior versions" (regarding
character data not supported by the client encoding)

We've decided to force the JDBC client_encoding to "SQL_ASCII". Per the
docs, "allowEncodingChanges" will allow "SET client_encoding..." execution;
However, I'm wondering if there is a way to force the connection to use a
particular encoding to begin with?

I've tried "props.setProperty('client_encoding', ...)" without success.

Thanks