I don't know that you can do this. $600k sounds small to you, but the people making those kinds of bets ($600k is a big bet, but presumably you're thinking of syndicating a bunch of smaller investors) are doing so on the premise that you're going to go on to raise a priced round, then a B round later --- ie, it's the same portfolio theory that the institutional VCs are using.

The thing I think you have to keep in mind that is that risk of failure (where "failure" is defined as "returning the same or less than the same money invested in low-risk investments would have over the same time period") isn't linear; by scaling down your ambitions, you do scale down risk, but probably not so much that you open up new avenues of equity investment.

I'm not an expert, but I don't think you're going to raise 6 figures on the premise of 6 figures ARR in 3 years.