As others note, use of a low resistance conductive surface is a bad idea.
Use of an entirely insulating surface runs the risk of electrostatic buildup which can damage PCB assemblies. The preferred solution is either a surface which is very slightly conductive and grounded, or supporting the PCB so no electrical contacts are made.
Spraying the bottom of the PCB with a conformal coating is a good idea.
This provides a degree of protection against contact but is more valuable as a protection against longer term contamination and as an ESD protection. There are numerous formal conformal coatings avail;able, but a cheap and reasonably effective coating is polyurethane clear "varnish" available in spray cans for general purpose surface coating purposes. The PCB top can also be sprayed if desired BUT all connectors and mating surfaces would need to be masked to prevent them being coated. Probably not worthwhile overall.