I don't know the total answer, but it seems like the hydraulic ram that is used in the steering assist will inhibit or limit the ability of the front wheels to turn based on road feedback.
We tow our Jeep behind a RV that has a long rear overhang. As we turn, say to the right, the front wheels of the Jeep first turn to the left as the rear swings out, then the wheels reverse to the right as the turn completes.
I've actually considered getting a hydraulic assist system, this might be a big negative for 4 down towing.
Call the manufacturer of the hydraulic assist and get their feedback.
Try it, observe the front wheel behavior. If the wheels don't turn easily enough, there will be a lot of tire wear.
Figure out some sort of hydraulic assist disconnect.
You might ask this question on one of the Jeep web boards to see what other people with Hydraulic assist have done. They may be trailer-ing their Jeeps.
Let us know what you find.
2002 35R Southwind, W22 8.1L Vortec UltraPower, 19.5' wheels
Toad: Wrangler, lifted and on 35" tires