Ruth, it's not going to be 'pretty dark', it's going to be pitch black on the cart path. If you aren't used to that kind of deep darkness, it can be quite disorienting.

I'd advise you to go down to Portofino early in your trip when there is a half moon so, if it's not cloudy, you'll have some ambient light rather than having to rely on the narrow beam of your cart lights. ...and on your way down, (which you should do while it's still light out) you should make note of landmarks (unique trees/plants, potholes, etc.) so that you have a sense of where you are on the return trip.

I live in a rural area with no street lights so I'm quite used to real darkness but I still find myself heading down driveways or veering off the path when walking or riding at night north of town.

Newfoundlanders are the only people in heaven who want to go home.