Since your source is located in the farfield I would use a plane wave for your excitation source. You can use the EMI/EMC template that will define a plane wave for you.
You can use as many field monitor probes as you like because they are computationally free but as you mentioned... that's a lot of data to go though at the end. You can plot all the probes on one graph and then pick the one that reports the highest field and ignore the rest perhaps. If many curves are selected on one graph, you can copy and paste (or export) all those curves with one command as long as the graph is displayed.