Good point. Insurance dictates everything in the US, although you would hope a policy that covers solo students would also cover lower hour instructors giving dual instruction.
The easiest option is always to get hired by the place that trains you. To them you're a known quantity rather than a risky curiosity.
You could also volunteer your services as a safety pilot / mentor for other hour-builders. Commercial solo hours can be done with an instructor on board to supervise. They'd get a lot out of it and you'd both log PIC under US regs.