My old boat said X#people and X HP limit, OR no more than combined weight total of people gear and motor. It would depend on how your boat's capacity plate reads. My guess would be that three adults would put it at or over the weight limit, even not counting gear, motor, etc. If you want an exact answer, weigh each adult, add their weights, then contact the PF&BC district office and ask their opinion on it.
I gotta go agitate the techies!