The predators that roam and hunt at night are also active during the day so whenever you free range you are taking risks, but they are more active in the dark. So yes, the risk is greater. I understand your concern. And to add to your concern it will soon be dark before you get home. You might want to add this to your considerations.
You could just leave things as they are and just open the pop door and take your chances. I know, you are looking for something better.
When I'm in that position I open the pop door so they can go out whenever they wake up or wait until I get home if I'm out late. But mine don't free range, mine spend their day in a well-protected run and inside an area protected with electric netting. They are pretty well protected from most predators all the time. So one answer is to install a run or an electric fence of some type to add to their protection level. That ends their total free ranging during winter but adds a protective layer to reduce risk.
As mentioned you can install an automatic opening, either on a timer or acting on a solar eye. Those can run on solar if you don't have electricity out there. That includes closing as well as opening.
Do you have a neighbor that can let them out and put them up for you? Unless you are good friends that could be asking a lot of them.
That's all I can think of. Good luck!
