I'm not sure why you need to use any URL. The register pubkey 8b8070fe 039df70c1c46425ae4d3be53892949e17bebcbe30f419132441faab92677b220f5 one seems easiest. But the checksum is only valid for Bitcoin testnet. So unless you specify either "Bitcoin testnet" or "111" (i.e. Bitcoin testnet prefix byte), it would take 112 iterations of sha256d to verify the checksum, assuming the verifier starts at prefix_byte = 0. That's not a heavy burden, but it seems unnecessary.
The URL was only needed in order to give the pubkey in a way that technically would match what CLAMour expects. I won't do this. I'm likely to go with the "register pubkey " approach.
I'll try to modify my copy of the clam code to have a "getpubkey" command.