If you take your time, you’ll be fine. Slow down and own it. I make a practice of saying “This is going to take me a while,” both to set expectations and to give myself permission.
Do not discount your rate.
If customers balk, explain that this is because of excess wool growth and that next year, it will cost less. There’s no need to make anyone feel bad for falling behind on shearing. We know how hard it can be to find a shearer, and how few of us there are. Tell them they’re doing the right thing, that things will be better in the future, etc. but also communicate the reality of the situation so no one is surprised. I use very plain language: “I never like to nick a sheep, and I will do my best to avoid that, but here is the situation with the wool…”
Adapt your technique.
Use normal equipment, but more of it.
I do not use 9-tooth combs. I’ve sheared sheep with multi-year growth just fine with my usual 13-tooth combs. Indeed, I’d be more leery of using a 9-tooth comb for Shrek sheep, as that lifted skin would fit too easily in the larger space between the teeth. No bueno.
I hope this helps somebody out there. Just take your time, all the time you need.