Chicken- the last coupla years i have been switching over from buckets to pvc sap sak holders using hose clamps & test caps. i haven't had a big problem with rain getting into the bags but i agree with ur philosophy. sap doesn't grow on trees but close enough to not have to use questionable sap that might taint the final product. i will pay more attention this year and see how tap placement affects getting stained sap in the bags.
mark