Securing Gutter Guards to Gutters Without Screws

I am planning on installing some type of gutter guards on my gutters soon. The previous owner of the house had cheap plastic ones that aren't very effective. The nicer metal ones all seem to require that you screw them down to the gutters. I am really hesitant to do that and would rather not drill holes in my gutters. I think that could cause them to rust over time and despite what the companies say, there is no solution that completely eliminates cleaning the gutters so I want to be able to take them off fairly easily.

Has anyone done something like this? I've thought about taking screen retainer clips similar to these:
http://www.homedepot.com/p/Prime-Line-7-16-in-Metal-Screen-Retainer-Clips-6-Pack-L-5797/100567475
http://www.homedepot.com/p/Prime-Line-7-16-in-Plastic-Retainer-Clips-4-Pack-L-5796/100581952
Or, I might be able to find some strong magnets to hold them down. The back end of the guard slips under the shingles a few inches so I just need a way to secure the front end to the edge of the gutter. I'd love to hear suggestions. Thanks for the help