Hey Jason!
The best advice I could give you is to simply follow your heart. If you have enough experience that you are able to do more than just a small game then don’t be afraid to go all out. I think starting small is great if you have a game idea that works well for that but don’t be afraid to take a major risk. It’s hard and I can completely relate to how you feel. I left a great job back in March to follow my dreams of starting my own video game company. Back in 2008, I was going to have a publishing contract and unfortunately lost it when Blizzard/Activision merged with Vivendi and shut Sierra Online down who I was working with at the time. Back then, if you weren’t an established studio, it was extremely hard as the indie space wasn’t fully developed to get any respect. I worked very hard on that for well over 2 years sacrificing and it was an extremely hard thing to go through after it felt like my dreams were going to take off, to put in all the blood, sweat and tears to loos it all in the end. Between the fall of Sierra and some other personal matters I was dealing with at that time, I needed to take a step back and refocus my efforts.
I was at my recent job and couldn’t stop obsessing about it and getting off the ground and after Microsoft invited me out there last Oct for the ID@Seattle event, I came back more inspired than ever to kick this off. Right now, I’ve basically started everyday very early and I go to bed around 5am almost every night and I have to sacrifice seeing friends or having remotely any sort of life. I’ve also lost friends because I am now considered the friend that never wants to come out. I do have a lot of close friends that completely understand and support it but not everyone does. I saved up close to 35-40K before I left my job and I’m basically on a do or die mission. It’s all or nothing and I believe I can do it and ever since getting the Nintendo back in '86, my life was truly never the same.
But to relate, I can’t tell you how many sleepless nights I have where I worry if I am doing too much or not focusing on the right areas. It’s a hard thing to experience and sometimes no one out there but you will understand how tough it really is. At the moment, I’m doing everything from the programming, art, modeling, uv mapping, audio fx/music comp, etc you name it but will eventually focus on being a great CEO and Creative Director once I can get a proper team established. Ever since I was young, I dedicated my life to learning everything I could about game development so it really helps at this early stage in the game (pun intended ;)) but still, there are so many times I sometimes fall into doubt. I have meetings with some major publishers lined up and I have probably a matter of 6 months to nail things down and get investment. It’s the scariest thing in the world but yet really exciting.
Also, I agree with Iniside not to get too caught up on design documents and I’ll tell you a funny story. When I met with the execs at Vivendi/Sierra back in 2008, I spent literally weeks on my design docs and it literally was I think well over 50 pages of stuff. I remember walking in to first meet Ross Erickson, who was actually 1 of 5 gentlemen at Microsoft’s Xbox Team that launched XBLA and decided their initial lineup before moving to Sierra so I was really excited just for the opportunity to talk with him. I first walked in and passed around stapled copies of my docs for my older XNA title and without batting an eye, became drink coasters for all of them. Inside, I was saying, man… that took a long time to make haha 
but quickly I learned design docs didn’t matter much and Ross was a great guy through out the meeting regardless of that. The reason why, at least in this instance, they wanted to play my demo and talk about it. The 15 min pitch turned into an hour of talking about the project and covered more within the first 15 minutes than the entire doc. It’s possible they looked at the docs later but I doubt it. I think in the end docs are good for an initial outline but they can also create early limitations and barriers so try to be as open ended as you can as long as it doesn’t negatively affect your ability to stay productive.
But from one dev to another my man, follow your heart and believe in yourself buddy and fight the doubt. No matter how hard it gets, just make sure you are prepared for the sacrifices you may have to make in your early strides to get your game off the ground. And don’t pick the easier game only because it’s less work, because amazing things can always happen from taking big risks in life. I feel for you Jason and I wish you the best of luck on your journey. I am not sure who says this quote or if I’m quoting it accurately but I’ll leave you with this my friend… take care
Also, I’d be open to helping start a group out here in LA with some of you from the community and having some meetups for some of us trying to start a company, share our stories or simply to recruit some team members. And to everyone else out there going through the struggle, stay strong, keep dreaming big and reach for the stars.