Topband: 160m mobile

[steve d]

I am pondering the idea of making a mobile 160m antenna. I have a Tarheel model 200 (older model, abt 7 years old now) on my truck and it tunes 80-10m. However, I know the efficiency on 80 (and 40) isn't the greatest. Even if I added inductance to it in order to get on Top Band I think the efficiency would be less than if I had a dedicated antenna. 
 
I have some wire to use for a coil - check out my blog post here: http://www.kc8qvo.com/2009/12/coil-wire-mobile-160m-antenna.html
 
Now, what to use for the rest of the antenna is the question. 
 
I was thinking of using an aluminum pipe, maybe 3-4" diameter and ~5 to 8' tall, for the base (like the screwdriver antenna base) and have that mount to the trailer hitch (insulated of course). Then put the coil on top. For the whip either a stainless whip or some creation out of thin aluminum tubing. I am thinking the band width on the tubing would be greater than a whip, but I don't know that it would make that big of a difference? Any ideas?
 
I am going to get with my friend to design up a coil. This should be fun. 
 
I do drive a truck and I am not affraid of a very large antenna. Though I can't get TOO big - I have had clearence issues on other antennas in the past. 
 
Steve, KC8QVO