I am not sure how it might affect a Sy, but I will share this. We mounted an Optima in a 2000 HD at work inside the cab after removing the rear seat. Then we started experiencing persistent electrical gremlins. Computer, ip, cd, etc. GM got tired of us. All wiring was checked, re-checked, replaced etc. by a master electrician. All wiring,grounds, battery were replaced.
Eventually, we just relocated the battery into the service body....problem solved.
I am still not sure why, maybe EMF?
Jay