Damn, I really thought we’d be able to find a way which didn’t create cyclic rules. So, I should firstly apologise for wasting time!
https://ourprism.org/* https://www.prismreports.org/:splat 301!
https://www.ourprism.org/* https://www.prismreports.org/:splat 301!
Perhaps above is the cleanest way of tackling it after all (based on this). The http/https will be handled automagically, I believe.