If you really want, you can add No Vending (NV), which means you can only sell produce in the bin, not selling it to shops, and no buying things from shops. So you can only get your produce going with Wild Seeds. Combined with only selling fruit, that could really make things especially difficult. It certainly isn't one I'd do personally, but if you really want a challenge, there you go.
NV would also mean you wouldn't be able to buy fruit tree saplings, which would be particularly crippling to your long-term profit strategy. Although I suppose once you find an Ancient Fruit Seed, you're off to the races regardless.
Hey, there's a challenge for you NAF (No Ancient Fruit). Prohibit yourself from planting it. Be easier than No Vending since you can get saplings, but it can really cramp your ramping.