A long-standing tradition for licensed AM stations is the "DX Test," also called the "experimental period." Both daytime stations and stations with limited night-time power are allowed to operate between midnight and sunrise with full daytime power and are allowed to try changes to their normal antenna during this test, which is intended to see how far the signal goes. Wouldn't it make sense for this privilege to extend to Part 15 stations? Of course, "full-daytime power" would never be more than 100mW, but "antenna changes" would allow trying normally banned antenna sizes, because we all wonder "what if?" So how about it, friendly government? Is it a deal?
I looked into taking advantage of the experimental period at a commercial AM station once... I found that you still have to submit paperwork to the FCC (including the $$ filing fee) to do one test.
BTW, I wanted to test FDMDV ( http://n1su.com/fdmdv/) at full power (1,000 watts) to see what decoding range we got...