This page is part of the web mail archives of SRFI 105 from before July 7th, 2015. The new archives for SRFI 105 contain all messages, not just those from before July 7th, 2015.
I'm not saying to put spec before rationale; just saying to put a bit more examples so that the readers can get clearer ideas of how srfi-105 looks like before he goes to rationale section. Exactly what you suggested. I don't think you need to explain why the rationale is so long--- if you need such an explanation, probably the rational is actually too long. I don't think it's too long, though; it contains valuable discussion. It's just that the reader needs to see what srfi-105 is before understanding "why not this, not that" rationale.