Hi Colton, congratulations! That is an awesome position to be in and could really be the golden goose for your financial future.
First thing I'd recommend is to be patient. You have a great opportunity in the casita to get your feet wet in investing. This market is hot, so no need to feel the need to jump in right away. Education is the best investment you can make, and it sounds like you're off to a great start here on BP.
On accessing your equity, a couple things may give you some trouble. In many cases you'll need 6 months of seasoning to access that equity (at a reasonable rate at least). Also, if you're only 1 year into that 1099 work, underwriters for more traditional financing will want to see 2 years of income/self-employment history.
My wife and I have are very fortunate to have a nice chunk of equity at a young age on our property. We refinanced into a very specialized 1st position LOC that's tied to a zero balance sweep checking account. That allows us to sit idle deposits/funds on our balance saving us interest, while retaining access to 80% of our equity. When opportunities arise, we simply write a check from our line and finance that ourselves. We plan to use that 30 year access to equity to build additional wealth, and snowball through investments.
I'm excited to follow along with you on your journey here, cheers!