I highly recommend (via my own experience) the Symposium Acoustics products. They make a platform specific for turntables and to solve the very problem that you describe. It's called the Segue ISO. There are several standard sizes to choose from and also they can be made to order in a specific size of your choosing. There are springs on the underside of the platform and you can choose to have the correct springs for the weight of your turntable. The platform performs at it's best when combined with Symposium Acoustics Rollerblock products. Those would be in place of your spiked feet. Contact the company and speak with Peter (company president/owner). He is extremely knowledgeable and helpful and will steer you properly. The products are fairly priced and deliver an outstanding performance value.
Symposium Acoustics: (symposiumusa.com)
Best to you on your quest.
Symposium Acoustics: (symposiumusa.com)
Best to you on your quest.