The players in one of my Pathfinder games have businesses they want to run, but we've hit a bit of a snag. I've looked at both the Pathfinder Downtime rules and the 3.5 DMGII's rules for running a business, but both of these options come up short. Here's my pros and cons of each, TL;DR at the bottom:

Pathfinder Downtime - Pros

• Lots of customization in rooms options, with mechanical backing. A tavern with a bar, common room, and cheap lodging earns a different amount of money than a lounge with a bar, performance stage, and well-furnished smoking rooms.
• Very straightforward system for gathering capital, in gold and otherwise.
• Pairs nicely with the Pathfinder Kingdom Building rules.

Pathfinder Downtime - Cons

• Practically no risk. Once a business is set up, it just quietly putts along in the background, accruing capital.
• Generally too cheap. You can build a pretty impressive business or stronghold with just a few thousand gold.

DMGII Business Rules - Pros

• Risky, varied events with lots of adventure hooks.
• Pretty decent moneymaker in the long-run.
• Lots of variance in profit, with potential for good months and bad months.

DMGII Business Rules - Cons

• Next to no customization. Pick a very general type of business (eg. criminal, service, shop), pay your money, and done.
• Very expensive up front, prohibitively so if you want to build in a metropolis, like the one where my PCs are based.
• Highly exploitable in a nonsensical way. Mechanically speaking, the best thing you can do is run your shop out of a shack in the woods.

So neither of these options is great for my group, so I'm looking for alternatives. Does anyone know of a 3.5/Pathfinder 1E-compatible ruleset for running a business aside from the two I've mentioned above?

Finally, I just want to acknowledge that yes, I could just handwave the whole thing, have my players pay an arbitrary amount and just "have a business" in the background, but that's not what my players or I want. We want something with as much customization and granularity in the ruleset as possible, with a potential for a decent profit. I'm pretty close to just giving up and writing my own ruleset for it, but if that ruleset already exists, no point in reinventing the wheel.