Wash rack

I'm wanting to build a simple wash rack outside an existing barn. My question is the height of the tie rail. I will use 2" oil well pipe and make a frame to tie to and anchor into the ground. I like the idea of a gate to tie to for multiple tie positions but I want to just weld a frame and make it permanent. I was considering having a lower rail at 3' 6" for calves and another at 5' - 6' for yearlings. Is that overkill? How high should the rail for yearlings be? Is it necessary to tie heads in show position to wash? Thanks.

We just put in a wash rack a couple of weeks ago.  We use a panel to tie to. I like the panel because of the multiple tie options.  I don't tie in show position, just snug their chin to a level height rail.  We completely cleaned out the barn and put in crushed rock (pea gravel).  In the wash area we dug out a pit about a foot deep and filled it with the rock and put rubber stall mats on top for them to stand on.  The rest of the barn including the pens is only about 4 inches deep.  We have no flies and can spray the whole barn with Pinesol in a pump up sprayer and then hose it down.  I'll try to post pics later.

I have considered digging a foot to foot and a half pit like okiegirl describes and filling it with sewer rock and topping with either rubber mats.  We only have a couple years left now, so probably won't but that seems like a great "poor man's drain field" solution.