I've put magnetic switches at opposite ends of a sled that goes in a 4" rocket (my Excel w/DD). By opposite ends I mean same distance from the nose, but 180° separated on the airframe. This has worked fine for me, the range at which the featherweight switch works with it's provided magnet is fairly short, certainly much less than the ~3.5" separation between the two. Now if they were side-by-side that might be a problem, and in a much smaller diameter rocket maybe it would be a problem. The other thing I've noticed is that the magnetic switch seems to be pretty sensitive to the orientation of the magnet, the way I have it mounted in some of my rockets requires me to swipe the magnet vertically along the airframe to activate/deactivate, and when I mount it rotated 90° in other rockets I find I have to swipe around the curve of the airframe to activate/deactive reliably. So I wonder if you might be able to place them more closely by having the two different orientations, I doubt that would be fool-proof though. I find that even in the right distance/orientation it is possible to get the switch to toggle twice (ON->OFF->ON or OFF->ON->OFF), so I try to position a vent hole right over the switch, both as a reminder of where I need to swipe and so that I can see the LED to make sure it turns on/off as expected.