Make it simple, and do as the buddhist monks do it, eat all you want before midday and then nothing,maybe some fruit ,but only fruit,not fruit juice. Whole fruit doesn't spike insulin levels.
I understand what you're saying but if you train immediately after ingesting then the insulin levels will fall quite quickly.
Sorry I mistyped. The glucosamine comment was true, but I meant that it's the isoleucine in BCAAs which can prevent or interfere with ketosis. Because of this, while on a keto-based diet, I only take leucine instead of BCAAs.
I've heard that spiking your BCAAs with extra leucine will also help to increase the leucine:isoleucine ratio which helps with the keto issue.