If you look in "regions" Long Island is there. They are holding 200, 300, 400k this year
https://rusa.org/cgi-bin/eventsearch...&sortby=region
Here is their webpage
https://www.lirando.org/
I didn't find a map for the 400k, but the 200k and 300k are all on LI. It looks like you could fit a 400k on LI, but maybe they don't.
400k course description
Brevet starts and finishes at Station Square in Forest Hills (NYC Subway and LIRR accessible). This ride will take the rider east to Ronkonkoma via the Grand Central Parkway & LIE service roads. Then the course mimics the Ronkonkoma 200K, heading east onto the South Fork including a dawn ride from Sag Harbor to Greenport on the Shelter Island south ferry before heading westward along the North Fork to reconnect with the LIE/GCP service roads back to Forest Hills Station Square. And returning to Forest Hills by the same route in reverse.