Insight.database and stored procedure output parameters

Question

My question deals with getting output parameter values back from a SQL Server stored procedure call with Insight.Database. If I declare a class, and then pass in an instance of that class, output parameters come back as advertised. But this has the drawback of making me declare the class far removed from where it is used. (And I only need each class for a single stored procedure call…)

If I pass in a local anonymous object, then the object can be declared right above the stored procedure call, keeping the code much clearer. However when I do that, the output parameters are not returned in the corresponding members. (But the in-going parameters do get passed as expected.) In other words, these do not work:

var transDetails = new
{
    Account_num = accountNumber     // in parm
    Trans_amount = 0            // out parm
};
Db.Execute("get_details", transDetails);    // Does not work
Db.Query("get_details", transDetails);  // Does not work
Db.Execute("get_details", transDetails, outputParameters: transDetails);    // Does not work either
// transDetails.Trans_amount is unchanged.

Is there an approach that declares the parameter object in-method with the Insight.Database stored procedure call, and yet allows me to get output parameter values back? Thanks.