Oh, NOW I understand what you're talking about. Using a regular orbital valve. I thought you were talking about something else, and was trying to imagine what those parts would look like and how they might work... So yes, I have seen this done before, or at least discussed. Don't remember, but I think it was on the Pirate forum. Can't think of any reason why that wouldn't work in any case.
No need to be concerned about using a double-ended ram with hydraulic assist. If you think about it, all you're doing is introducing two additional pivot-points. You could install a double-ended ram and connect the two front wheels with two shorted tie-rods, and it would function exactly like the stock tie-rod (if you didn't change anything else). There's also one big advantage to using a double-ended ram, as opposed to a singe-ended ram - the balance. A unbalanced single-ended ram isn't going to give you the same nice balanced feel that a double-ended ram will, when turning one direction vs. the other.