Larry, respectfully, I do have significant experience in this area.
Departure procedure obstacle clearance does NOT require you to cross the end of the runway. On a diverse departure, any turn in any direction is protected as long as it's initiated 400 feet above the runway and no earlier than the DRP, which is 2000 feet down the runway. That's all right out of FAAO 8260.3G, para 13-2. Even if you turn 180 degrees around, you're still protected.
If you're thinking of a DVA, which is used for radar vectors below the MVA, that is evaluated in essentially the same way.
If the departure procedure says "climb to XXX altitude and turn right heading YYY", you do exactly that, regardless of where you are in relationship to the runway when you reach that altitude. The default is 400 feet AGL. If as part of your clearance, tower says to "fly heading ZZZ", when you get to 400 feet, you turn - again regardless of where you are in relation to the runway.
A local example has this in the SID: "TAKEOFF RWYS 17L/R: Climb heading 176° to 1800, then right turn heading 201° or as assigned by ATC". 1800 is about 500 AGL here. You take off, and whenever you get to 1800, you turn either to 201 or the assigned heading. There is NO need or expectation to wait until you get to the end of the runway.
Because, again, how do you know where the runway is when you're in IMC? You don't. So the obstacle clearance is not, and cannot be, based solely on that. Yes, there is a part of the obstacle clearance surface that starts at the DER, that is to protect the airplanes that use up the whole runway and then climb at the minimum climb gradient. But there's also protection for airplanes that take off sooner and climb quicker.