Thanks for the info - you can do up to 4 letters and submit it (without cost) to see if it's available.
The plate only takes 3 letters. Actually the plate would be 5 letters. The last 2 letters are US. The US is on the right side and vertical, and designate veteran.
One of my bikes has PGR, and the other is FLT. I tried to get FLTR, and the Sec of state people said 3 letters only.