Just write private pilot and single pilot. It's irrelevant to the medical anyway. Probably just for their records. It doesn't matter whether you fly, sorry flew Concorde or an ultralight the medical standard remains the same.
I've just renewed mine complete with high blood pressure (under medication) and with my eyesight heading unerringly towards reading glasses. Don't worry too much about the medical. After all there are many older pilots with all kinds of niggling infirmities. I have to admit I never worried about medicals until they found high blood pressure. With that being treated. I don't even have to worry about that either.