As someone who had to rent many cars traveling domestically in the states while under 25, there were a few tricks I would have to use. One was that New York had a law that over 18 could rent a vehicle with no fees past whatever insurance directly charged the rental agency (so usually fee-less) which was a big help. Sometimes you could arrange the booking in such a way you rented from NY and picked up the car in another market in the country, but very ymmv. Under 21 was otherwise just about always prohibited with the notable exceptions of U-Haul and Penske (if you really needed wheels, it was many times the ONLY options). 21-25 usually had outrageous fees (literally as much or more than rental cost) except with certain credit cards and corporate codes you could get them waived or reduced to a few dollars a day extra instead. And the last but least ethical tip would be to have a colleague as primary driver and only be a secondary driver as in my experience they only ever would bother with the age of primary driver. Your comment had me check and looks like only a few places seems to have that under 25 restriction for secondary driver, and honestly they are places that I can personally say didn’t check previously so it may have changed or also be very ymmv.