I am sorry but these new opcodes added to proposals will only delay or cancel them forever. I understand you like 2 things combined on the stack, OP_CAT etc. but this brings a lot of complexity in something that needs to be kept simple.
If we ever get OP_CAT, maybe this could be possible with OP_SHA256 and OP_CAT at that moment.
Its better if we get OP_CTV activated first instead of trying to build the next Great Covenant Proposal.