I had one really good year as a freelancer and wound up spending the money I'd put aside for taxes because a client who had been paying me a retainer suddenly cut me loose right in November (the absolute worst time to try to pick up work as a freelancer). I was burned out and depressed about losing the gig so I didn't work for almost 8 months and wound up burning through the $30k I had set aside for taxes. I missed filing my taxes or an extension and the penalties just mounted until eventually my bill came out to about $40k.
After "negotiating" with the IRS (complete bullshit, they tell you how its going to be and you just have to deal) They decided that I could pay $2k a month on a $80k salary (how insane is that?). I lucked out and got a job that paid me almost double about 3 months later, if not for that I'd be toast.
Its easily the most stressful thing that has ever happened to me. Tax Lawyers were rude and dismissive ("Maybe get a cheaper car?" said one) once they realized I wasn't Mr Moneybags. And nobody can or will loan you that kind of money.
The only thing I can offer up apart from the Offer in compromise is that once you get the bill under $25k. You can negotiate directly with the people you talk to on the phone, once your bill is over that, everything they say/offer you has to go to some faceless manager somewhere, and it can be rejected and ridiculous alternative unilaterally offered back to you.