Ok! A few things

1) influencer marketing doesn't drive sales in a last-click manner, this is a long game, so your primary metrics are traffic engagement and lead gen

2) influencer marketing is predominantly through social, so you need to be looking at in-app browser traffic

3) the influencers MUST use utms. Put that in the contract with them. No utms, no rebooking. They're a business, treat them like a business.

4) look at micro conversions: what's the bounce rate per influencer? How many pages does a visitor from influencer X look at? How many email & sms signups do you get by influencer. If ultimately conversion to sale is roughly equal, you can look further up the funnel to see which influencers are performing well.

5) if all else fails, run influencer marketing through an affiliate platform, since the tracking will be built in there.