I wanted to second the bit about vibration isolators, but I also see your in Florida, it seems over the last few years that your state has been getting very strick on generator installation, where they can be located (minimum number of feet from house, no opening windows or doors within X feet, not within X feet of property lines, etc.) They are also requiring pads be signed off by engineers, and I think part of that spec is minimum of 6 inch thick concrete unless using special high PSI concrete. Some generator installers in FL have even started using pre-built engineered synthetic pads to get around the engineer sign off on individual projects. As I understand it some people in FL are opting to mount their home standby generators on trailers parked next to their houses just to get around all this.
Ike