A bit of a late reply, but whatever:
A bit over a year ago,
an updated run of Paper Mario was posted at speeddemosarchive. It beats the game in 3 hours, 38 minutes (SDA timing).
The strategy used there is pretty much optimal. Barring any discoveries of helpful glitches or frame-precise tricks, I would be surprised if an optimal TAS was better by much more than 5 minutes.
The main strategy is to avoid all optional fights, and use Bow's Spook attack against ordinary enemies you're forced to encounter. Bosses are taken down by Power Bounce/Jump bolstered with Mega Rush & charging, helped out with Parakarry's Shell Shot.
Money is not an issue -- you only need 50 coins to get Speedy Spin before Chapter 2. Now, money would be an issue in a 100% run -- you'll need about 2300 coins to purchase all of Rowf's and Rip Cheato's stuff. But that's easy -- just abuse the 9-block Jump Attack minigame to win 900+ coins each time.