All the rest of your plan sounds great for storing seeds except this one. I do not think you want the RH that high for seed storage. Please correct me if I’m on the wrong track here folks, but I’m pretty sure I would have had mine down around 35% or even less when I froze them. I have successfully germinated seeds frozen for over a decade and they behaved as though you just bought them, it’s really amazing. Desiccant packs and/or rice are all you need.
I put the seed packs in a cooler with cooler packs and let the seeds warm up slowly overnight, but I haven’t compared that with just taking them out so I really don’t know if that matters. Freezing seeds for indefinite storage really works.
edit They were stored in air tight 125ml canning jars, with much of the space taken up with little plastic bags of seeds and desiccant.