magnetic paint
I am a manufacturer of magnetic paint. My paint can be found at
www.lyt.com under the name of Lytle Magically Magnetic paint.
The magnetic paint you mention is made by many manufacturers and contains the same ingredients to make sheet magnets stick to walls. The paints contain millions of microscopic particles of iron dust that with enough coats of the paint, magnets will stick to the wall like they stick to steel.
Here is the rub. Ordinary magnets will not stick to the magnetic paint because they are too heavy for their surface size and the paint does not impart enough steel or iron particles to make it as magnetically attractive as solid steel. Your magnetic cup hooks would fall off, especially if the motor home were moved or driven on the roads.
Magnetic paints are made to be used with sheet magnets. They are not so strong as regular heavier magnets but for their weight, they are quite strong as they spread their power out over many square inches. They are easy and fun to use and for use in the home are wonderful. We make many lines of magnetic photo and picture frames that can be used on a wall painted with our magnetic paint.
I don't think cups dangling from hooks would work out too well in a moving motor home even if the hooks would stick to the surface. The cups would swing back and forth and quickly make circular scratches on the surface.
I hope this is of help.
Sincerely yours,
David B. Lytle
Lytle Magnetic Photo Products