Hi Mike,

For the unlicensed US lowfers, the main barrier to big TX antennas is rather 
significant:

FCC 15.207(b) "The total length of the transmission line, antenna, and ground lead 
(if used) shall not exceed 15 meters. "

Despite the lowfer urban myth, I'm afraid there are no exemptions for huge 
"non-radiating" horizontal sections in tees and loops, so the 15-meter rule 
leaves you somewhat limited.

Keep rooting for an LF ham band.

73
Mike W2AG