I’m no expert, as I have never kept scarlet kings, but I sure do love them! My opinion, though, is that these snakes are fossorial in nature, which is a bummer because they’re so pretty to look at. My suggestion is based on how frequently they are shown to be discovered under cover. Tree bark, rocks, etc. It’s not a snake people find rummaging about, like a garter snake or a racer.
That being said, you may need more appropriate cover/hiding spots. Less lighting. Certainly not UVB. Nighttime feedings.
You may not get the joy of watching this kind of snake eat, basically. They are shy by all counts I’ve seen them depicted. I live in Pennsylvania, so my knowledge is limited to videos and good books. Humidity and temperature will be very important in success with scarlet kings, and if it were easy, I think they would be far more popular to keep than California kings and even corn snakes.
I wish you the best of luck, I have loved this species ever since I saw them in Peterson’s field guide when I was a little kid. It’s just daunting to think it’s a kingsnake, but is so much more difficult to work with than other kings. I hope someone cracks the code to easy keeping with these guys, I still hope to get some for myself!