Did mine last month too....took 15 minutes.....
As far as the law....here's the law for IOWA, just in case someone needs the info:
321.37 states "The registration plate issued for a motorcycle or other vehicle required to be registered hereunder shall be attached to the rear of the vehicle."
321.38 states "Every registration plate shall at all times be securely fastened in a horizontal position to the vehicle for which it is issued so as to prevent the plate from swinging and at a height of not less than twelve inches from the ground, measuring from the bottom of the plate, in a place and position to be clearly visible and shall be maintained free from foreign materials and in a condition to be clearly legible. "
I've been pulled over for speeding with the plate sideways, but officer never mentioned it.....nor did I end up getting a ticket.....was more interested in chatting about the bike.....
Older law also says you can NOT have ANY of the lettering covered on any of your plates...and there was a big news article on it the other day, they started writing plenty of tickets for it...must be running short of funds....