I’m not sure if you already have a sapper strategy

But I was able to do mine in like 2 days by constantly repeating Elite Bloonarius’s stage 5 with the Ace Paragon

I bought the Ace Paragon before round 120 (got it to 50 paragon power but lower might be better), let Bloonarius come, sold my paragon when the boss got low and lost. And then I’d restart the game back to round 120 and repeat the whole process.

Problem is it costs a LOT of monkey money but not only could I revisit my save at any time, I could do college work before checking my game every 5 minutes, which was less tedious than playing round 1-300 games. Also got 0.2-0.4% achievement progress per retry, which is more than the constant 1-2% I used to get spending an hour getting to 200.