Take a look around on ebay in the photography section for inexpensive light stands. They have a wider leg spread than the usual music stand.
Also, I have seen home made adjustable poles, that have a spike on the end, that were built with common materials. If I remember correctly, the head of a spike was welded to the head of a bolt that extended through a hole in one end of a steel bar, that was stout enough to be used to step on to drive the spike into the ground. The bolt was large enough to make a close fit into the end of a piece of electrical conduit, and both were cross drilled for a roll pin. At the top of the tube, a bushing and thumbscrew were fitted to adjust the height of a rod that fit within the tube. I hope that this rough outline is of some use.