A few free evenings and an email-copy habit — what could come of it?

You could offer a small brand to redo their abandoned cart flow for a share of what it brings back. Easy to measure and low risk for them

Do you specialise just in ecommerce? Or do you think your skills can be applicable elsewhere? In a way (if I understand correctly) you are good at "waking up" customers or potential customers that either have been inactive or completely dropped off - that's a problem pretty much any business has. If so - you can actually in a way create the demand - huge number of business owners are sitting on client lists they do not at all use (or use badly and rarely) and they don't even think about it. Start contacting those not with offering anything but with a question - when was the last time you wrote to your clients? What did you get back? Throw some stats on repeat business - it is insane the money people spend on acquiring new clients when once someone has bought from you once they are so much easier to bring back and statistically they buy more if treated right!

I think you should expand what you offer as far as copywriting. Leverage those funnel skills to include softer brand awareness touches, specifically on social channels where text is important. The more you know about various industries the better, and I think this could net some larger retainers and freelance copywriting clients.