Consider these (from a guy who has been 45 years out of High School):
* Where are the magnets going to be mounted in relation to the chips in the pixels, or the wires going from pixel to pixel?
Magnetic flux only is strong enough to interfere for a short distance from the magnet itself. it is dependent on the strength of the magnets, and other factors.
* Are you talking about mounting the magnets to the PVC and/or the house itself?
There have been examples of some here that mounted to the house using magnets. In one case, the magnet was buried into the house itself (in mortar beds mostly) and then a steel piece attached to the light bar. In other cases, the exact opposite. The magnets were mounted on the light bar, and they put steel into the wall (again, usually in brick, but other substances were talked about.)
One thing I have been trying to answer for another project, magnets are used to smooth out power line chatter, which in many cases looks like digital transmissions. Our pixel digital outputs are "weak" compared to other communications lines, so would they be "choked" to the point of not working well? I don't know. Anyone else have any idea?