I would keep the conversation short, and instead of going fishing which you don't enjoy ask her to join you at an event (not a date, not dinner, not something intimate but something fun). Maybe a ball game, or if there is a new event at a local museum, or a wine tasting or some sort of out dour food/wine festival. Tell her you are going, and it would be fun if she came along.
Keep the phone conversations somewhat relaxed and treat her like a friend that you are interested in getting to know better. Normally I would be more aggressive but in this case she is friends with your wife so her guard will be up extra high. Don't act like her friend though because ultimately that is not what you (or she) wants. Only be her friend on the phone prior to the 'event'.
Bill