Richard: 

I'd look for a telescoping mast that could extend to 25/30 feet and like Ron suggests, extend it to only 15 or 20 feet for strength. You would then need some method of guying it so it could still be able to rotate. 
I'm thinking that you can get guide collars that have an inter section that rotates or you could rig up a thrust barring to probably accomplish the same function. Next, I'd look at the Yaesu rotators, you can remove the glass from the controller and gently touch the hand while it moves to the various headings, unless you got the bucks for the Hy-gain controller which permits direct access to your headings via key pad or you can have a Ham-X type modified with EZ rotator kits and so on, still probably more than what your interested in. 
I trust your looking at a 5 band Hex beam? This bean could be set up to use a lite duty rotator, Yaesu 450 or Hy-gain CD-45 type. Thats the root I'd go. 
The Hex on a rotating 20/25 foot mast, turned by the Yaesu 450. So on that note, talk to DX Engineering to see if they can put a complete package together for you. 
Keep in mind though that the biggest beam on a telescoping mast might be the Hy-gain TH-3 type or Cushcraft a/X type, no more than 35 pounds. Anything bigger than that then your looking at stuff from US Towers and such, costing you in access of 1500 for the support tower alone. 

HTH and 73: 
Michael VO1AX