Yes I have a suggestion Jim, consider doing without the refrigeration.
Boat refrigeration is inherently wasteful of energy. If you are only doing coastal cruising that''s probably fine but in that case a well insulated ice box should be good enough. I''ve kept stuff for up to a week that way.
Save your money and just take your ice with you. I know that may not be the answer you were looking for but the reality is that most of the systems I have seen suffer the same problems.