Silicone Heater

I would go with 220V every day and I really think it is a less fire hazard that the 24V option as you would need so much more current to reach a decent power. I have a 1000W heater and it only takes about 5 amp

If same power with 24V heater then we are looking at 40 amps and that requires a lot from cables and connectors and PSU

You do need a SSR – A Relay switch to control the AC current and those can fail so it is advised to have a thermal fuse that can cut the current if SSR fails

And make sure to ground all metal frame and bed parts