Anybody ever build their own LISN? Need advice for design of high current air cored inductor!!

Mainly due to lead time issues I am considering building a couple of CISPR 25 compliant LISNs for automotive EMC work. These have a really simple network so the only real challenge is an air cored inductor capable of doing (ideally) 100A continuous. Any advice folks? Frequency range is 150kHz to 108 MHz. Is it really as simple as some turns of "Litz" round a former? I have never designed an air core inductor in my life other than for high current switch pulse testing when the "design" was a couple of turns of equipment wire that was kicking around with cable ties to stop it leaping apart!!