Let's see how your mood is when diagnosed with skin cancer! Not that I would wish it in anyone, but intentional exposure to damaging UV when there are safer alternative treatments for SAD does not seem like a sensible course of action.
Put it this way - I would get more UV collecting my mail in summer than you would on a tanning bed for a couple of minutes. And I haven't dropped dead. But a bright sunny day does make my mood brighter.
Vitamin D deficiency and depression are much bigger issues than UV over exposure.
I know it is tricky, but there are situations where there is no such thing as 0 risk, you have to optimize for minimal. Making 0 risk of one thing frequently increases risk for others. In this case, improper active vitamin D levels increase risk for lots of ailments, far more than a few minutes of UV exposure does for skin cancer.