help! how can I keep crusts crispy in 90%+ humidity

https://www.google.com/search?q=site%3Athefreshloaf.com+crisp+humidity&udm=14

If you don't have air conditioning to reduce the humidity you may not be able to solve the problem completely.

It often happens that the bake is ended when there still is a high moisture content in the loaf.  That moisture will tend to soften the crust as it tries to work its way out.  This will be for any humidity but the softening will naturally be more pronounced with high humidity, The standard cure is to bake longer, but at a lower temperature so that the crust doesn't keep browning too much. Sometimes this is done by leaving the bread in the oven after it's turned off.

How can you tell if there's too much moisture, apart from finding that softened crust? Nothing is guaranteed but measuring the temperature at the center of the loaf with a probe-style thermometer (also called a "meat" thermometer) is helpful. You want the temperature of a lean loaf to be close to the boiling point of water, which is 212 deg F at sea level (New York City is at sea level).  I usually try for 208 - 209 deg F but I don't have the high humidity problem. You should probably go for 210 - 211 deg.

You can still have quite a bit of moisture even at those temperatures, because the evaporating water will keep the temperature from rising all the way to boiling.  So you may need to keep baking longer even if you hit that temperature range. Make sure to reduce the oven setting for this last part of the bake.  I usually use 375 deg F but with your humidity you may want to try 350 deg F.

Another approach that sounds reasonable but I haven't tried it is to have a bread storage box that you can dehumidify.  There are various moisture absorbing products you can buy and maybe using some of them might work. You could put them into a cheap styrofoam cooler. B&H Photo (right there in NYC) sells an inexpensive device and perhaps something like that might do the job:

https://www.bhphotovideo.com/c/product/1377864-REG/ruggard_pdc_rd_portable_dry_case_renewable.html

Of course, anything that absorbs water will have to be discarded or emptied from time to time, and that's another consideration.

A final consideration is that a very dried out loaf will have a different mouth feel and even flavor than a moister bread. I don't happen to like a very light airy dry bread so much but that's a matter of personal taste. You may have to settle for toasting your slices of bread - if so don't dry them out as much.

Good luck!

TomP