GSDad,
This one gets talked about every year. Having already been through this, here's how it went for us.
Club essentially took precedence. Club games over anything, not normally an issue because of weekend games. Club practice over HS practice. (However, he went to HS practice for about an hour before going to club practice, and would leave HS early.) HS games over club practice.
In our case, the 2 years that we did it, the HS coaches were also involved with the club, so all understood. It was something that was well understood before the season started. The first year he saw playing time in each match, some more than others. The second year he started all matches.
In our specific case being at a SCISA school, it was to play on the varsity team, not the JV team. So I can't answer with respect to JV.