Bummer about the requirement for wheels, Dennis. Obviously the (bloody) local politicians are after tax revenue. Wheels will be an embuggerence as it will allow a good wind to get under it causing all sorts of damage. I suppose you could either jack it up to attach the wheels when required for shifting it or simply 'fake' it.
My advice on the stand-off electric fence will allow you to take the 'long view' regarding type of fence you'll build. It may be for a horse now, but what could the paddock be used for in the future? It's prudent to get it right the first time especially regarding the cost.
And that leads to a futher question... is this paddock a 'one off'? You'll save a great deal of money, particularly with a contractor, if you make a number of paddocks at the same time. You won't need as many H and/or corner braces & can arrange the gates in a 'Y' formation for ease of transfering the stock between adjacent paddocks...