This is basically what I was doing before.
I’m not convinced that the ones I’m currently using are best. Whiteboards are pretty slick and so the ones above only hold about 3.5 N. I’d like to get that up to at least 5 N, so I don’t have to reinforce anything.
And here is a slo-mo video of me using magnets with a horizontal spring.
Teach. Brian. Teach. 
Try https://www.sciplus.com/strong-mounted-pickup-magnet-3835-p
or https://www.amazon.com/Magnetic-Hooks（7-Strong-Neodymium-Magnets/dp/B07JG8C9DC