Thanks again Dave!
I was thinking about simply dropping the filter in and out, since my airtrap is U shaped, with a lid that sticks out the top of the case. I don't think I'd have room to fit a bypass, but I sure wish I had thought of it, before I put it together: I might have tried to squeeze that bypass in there, somehow!
zoom314: thanks for the tip. The Vortex unit looks nice, but I was simply looking for a filter, not an entire pump and filter combo. It's also outside my budget, and of course, I don't need the active charcoal portion, since I won't be filtering for microbial/odor/taste
I'm still going to go ahead with the 5 micron sample sheet. I'll make a cone shape with it, and add a ring so that it stays on top of the airtrap, capturing all the flow. I can then add a pull out pin/wire, so that I can remove it, simply by uncrewing the cap that will be sticking out the top of my case.
If I drop the backside cooler, I can rebuild the filter with 150 micron mesh, and just leave it in there, if it's not too restrictive.