Hi Glyn! I saw your question and feel your frustration at the non-answer answers the QB team provided.  You very clearly stated you trade and want to record the transactions - you don't want to accept Crypto as a form of payment and you certainly don't need their help choosing an Exchange as it sounds as if you should be giving them advice on that matter, not the other way around. 

I did find something that might help though.  I tried posting the exact link but this forum will not allow me to include the entire website link - it keeps deleting a central portion of it so all I can do is tell you how I found it. Do a search for "Importing bitcoin sales into Quickbooks" and you should see an article from a site called bitpay.  I used Google to find it but I also tried it with Bing and both found the website this way.  Hopefully they will allow at least that much information to post.

I'm not sure if it will be a total solution for you since you trade in much higher volume than my company does but it could be at least a step in the right direction or give you an idea of how to adapt what they started to a model that would fit your situation.   Happy Trading!