My personal advice is that the schools you are targeting are probably within your reach. I might add a couple lower schools to the mix just to be on the safe side.
A few comments to help you out:
1) Only retake the GMAT if you really believe that you can improve your score by atleast 30 points. Anything less will really just be a waste of your time, and in fact, you would have a large chance of lowering your score b/c the test has only gotten more competative since you took it, and you haven't studied in year(s). Plus, the alternative transcript you are putting together is a great idea, and I'd encourage you to continue. Stats, Accounting, and Calculus are great. Plus, UCLA offers an extension called "Managerial mathematics for Management" (
https://www.uclaextension.edu/r/Course. ... 0&dc=MGMNT) which is directed towards MBA hopefuls.
2) You are really going to have to figure out a good story for the Peace Corps (PC). As great as the PC might seem, this type of work isn't actually looked upon that highly by Adcoms. The reason for this is that most people that go to the PC after working in the corporate world are looking for a change. They either hated what they were doing, or have no idea what they want to get into, or just can't handle being a working professional. The fact that you went into a startup after returning is only going to perpetuate these thoughts. Adcoms want people that are extremely driven to achieve their goals, and spending 2 years not trying to achieve those "goals" may make it look like you don't have any direction. My advice is to really start taking that direction at what you really want to do. Even if you don't know, formulate a stronger story than "a Socially Responsible Business". This is too vague, and will not make the Adcoms say "LETS GET THIS GUY! HE IS GOING TO BE SUCCESSFUL". Tell us what kind of business, how, when, where, and how XYZ business school will teach you XYZ skills to take you there. And with your XYZ skills from your previous experiences will be a match, and how you experiences will now only help you improve your classmates but make you successful moving forward... yada yada yada....
3) Also, at this point, I don't think taking a new job will necessarily help. You are 28, and you'd have to put atleast a year or two in at a new job to really get full credit for a new position. Once you hit 30, you will be slightly less appealing to full time Bschools. So if you do really want to start your own business, the experience you are gaining now might be great for that. Plus, we all know that people in small companies, especially startups, do gain insight about business creation that persons in the corporate world do not. Although you do miss out on other corporate experiences that business schools like to see. So it's a trade off.
4) Like you said. Keeping a consistent message is key. This is why your Peace Corps explanation will be paramount. I would not mention your more traditional route posibility after the MBA if you also decide to go the entrep. route. It will make you look like you don't know what you want to do. Make the Adcoms know that you're going to do this with our without their school, and be a huge success.
Best of luck to you! I hope my words are able to help you on your journey