lol that's cute. I'm glad to help though!!
Might I suggest a nice 1.5 or so inches of gravel on the bottom and some sort of hide place for him and silk plants. Make sure not to use plastic ones because those will rip your Betta's fins! A good test is to find some old pantyhose and run them across and ornament and if the hose snags then it's going to snag your Betta's fins as well and possibly rip them, they're very delicate. So Silk plants are the best way to go, silk or fabric.
Betta's come from Rice Paddies which are endless fields of water with tall grassy plants and other various plants, so they're used to a place with crowded plants that they can easily swim through. Sometimes they get scared of big open spaces, it's not so much that they're scared of a bigger tank size but they don't like the big open spaces. It's like in Finding Nemo when they go off the edge of the reef, it's super scary down there and there's a whole bunch of predators that you don't know about! Of course your fish doesn't know that there aren't any predators about but they will still feel unsafe
EDIT: On the opposite side you can leave the bottom bare of gravel or substrate if it's easier for you and then just get the plants and a hiding place
I also have a bare bottom tank and my fish does fine.