I believe someone (Passinwind) provided a link to a pole mount with a design that is totally external to the cab. You might want to PM him about it.
Regarding low end response when raised high off the floor, any cab will sound a bit thinner and more midrangey due to the directional mids being closer to ear level, and also acoustical coupling issues (once you get the cab up that high).
However, IMO, the Thunderchild will have less of an issue with this than most other cabs. This is due (IMO and IME) to a couple of things:
1) The super duper woofer with all that xmax and mechanical 'power', so you can dial in a little more low end without the cab farting and dying like most small cabs
2) The VERY even midrange response through the upper mids results in MUCH less honk than most other cabs, which means it won't sound quite as unbalanced in the upper midrange, even when raised off the ground a number of feet.
So, I think this might be a good choice for you. The Acme cabs are another execution that behaves quite nicly up on pole mounts, even in bass heavy contexts.
IMO!