1) Get the notes done in session. If you can't do that, consider reducing the information in your notes. There is a reason that psychotherapy side gigs are more common than paperwork heavy gigs.
2) Remind me, what's that cognitive distortions where someone says "This outcome is a definitive evitability."? (hint hint)
3) Burnout is caused by low social support, a lack of control relative to reward, and some other factors. You are literally in control of your schedule in PP. If you're getting burnt out, then gradually reduce your work until you can handle things, maintain social supports, EXERCISE, etc.
4) IME with burnout, some distress can be caused by a failure to truly accept the life you chose. You've chosen to work late. Normal life responsibilities don't change because you changed. How have you accommodated those life responsibilities now that you have a NEW schedule? Are you trying to work until 9pm M-F, and then expect to have normal Saturday & Sunday? Are you expecting your best performance levels on your average day, or are you accounting for low productivity days? What is your schedule for chores? What are your social responsibilities, and how much do you care about that? Thorough planning can make this very easy.
5) Is additional work worthwhile? I would recommend looking at your living expenses BEFORE PP, and AFTER PP, to see if it is worth it. Are you ordering grocery deliveries, Ubereats or Amazon stuff more? Are you sending your laundry to the cleaners more? My expenses significantly change around 70hrs/wk. That has to be taken into account, when deciding about if the money is worth it.
6) What is your long term purpose for this side PP? If it's just money, you should be able to explain the specific amount you want, and the money's specific purpose.