You're near Indianapolis, so a 7-8 month mow season? What are you going to do for income those other months?
I'm on year 3 of a "never supposed to get this big" solo part-time OP. I invoice around $1000 a week, mowing only. (With a day job.) A couple thoughts...
* Residential customers suck. Not all of them, but by comparison...
* Small commercial accounts are where it's at, for me. They're far less picky, more dependable for repeat business, and there's little hassle over invoicing or payment. For a moonlighter like me, these accounts work out well, because I come and mow after business hours, so there's no disruption to their business, and it makes it easy for me to come do the work.
* Mowing 60-80 yards solo, is going to be exhausting. Unless you're talking about the ideal scenario of 5 cookie cutter lots in a row, at a time. It takes time for those to "grow" from 1-5 houses at a stop.
* I do some sub-contract mowing for a friend. This might be an avenue if you're super critical to your current employer. Maybe save this conversation for later. If you leave, and he doesn't have a "mow guy", then talk to him about doing the mowing for him. Expect him to keep 20% of whatever he's charging the customers. This would allow you to supplement your customer base with his, and help you both out. Go in with an understanding that the situation is flexible. He's free to add/remove accounts, as are you. Agree on terms, and do good work so that it's a mutual win-win.
* Website - Be very careful when you do your domain search. I don't know what kind of domain lookup registry there is, but I lost my preferrerd domain name by not being ready to commit... I searced, found that it was available, procrastinated, and it was gone when I came back later. Someone snatched it, and it's offered for sale for ransom basically... SO - When you do your domain search, have your credit card with you, and BUY IT RIGHT THEN. You can actually buy the domain name for a few bucks, and don't have to "publish" the website, so it doesn't cost much to buy it & hold it. But don't mess up like I did.
Also, .US domains (any .country I believe) registy info is public, meaning the name, phone number, etc. registered to that address becomes publically visible. The Indian tech people will WEAR YOUR PHONE OUT! trying to get you to buy garbage. SO, if you get a .US domain extension, use a burner phone number when you register it. Nothing is more frustrating than wanting customers to call for quotes, and it's actually the Indian tech spammers bugging you...