SSRs can fall under "switches", "switch units" or "motor controllers" depending on their use in the circuit.
The reason for the low current limitation on "roll your own" series combinations is because they are essentially acknowledging that below those values, the potentially destructive energy is low anyway. That doesn't mean you can't get there with larger fuses and devices, it just means that UL will not allow it without testing.
I think that your only choice is to search out an SSR that has been tested and listed at a high SCCR in combination with a protective device (usually a fuse) by the manufacturer. People like Siemens, Schneider, those kinds of companies with the deeper pockets to pay for the testing. I have also seen an article stating that Crydom has done SCCR listing of their SSRs with fuses up to 100kA, but a search of their website gave no results. Might be worth a call to them though.
Many people are shocked when they discover I am not a good electrician...