You kinda answered your own question...the longer rods make a delicate dry presentation easier, but your 30 ft. rivers and my creeks I find myself fishing a lot of terrestrials, and frankly they work better if they " splashdown", so the shorter rod and sloppier presentation isn't a hindrance. Besides, I'm not good enough to get the advantage out of a rod that can present a fly " just so"..
A short one would be fun on water that size...say about a 7.5 footer??
Just my 2 cents...
Ingwe

"...the left considers you vermin, and they'll kill you given the chance..." Bristoe