Yes, I thought about setting this up in a more formal way but didn't do anything about it yet.

I was thinking about a simple website which acts as an escrow for the funds.

It could work like this:

This means you can pick multiple days. The amount you bet just determines how much of the pool you get if you win.

Now that I think more about it... this doesn't sound too hard to code up, lol

Hopefully, I will start coding when I got home in a few hours lol