Hrrmmmm, how about a "clothes drying shed"? The hot air would be channelled down using a solar vent fan. If you are worried about musty attic air "soiling" your clothes, then use a heat exchanger of some kind. Hmmm. Maybe not too efficient.
But maybe it's even simpler than that. Imagine a black shed with a closet clothes poll in it. Just put the wet clothes in there, close up the shed, and let the sun do the work. Put some holes in the roof and near the floor to allow for heated updraft to let the moisture out.
I trhink it would be super easy to do.. all you would need is a long flexible tube spanning the length of your attic positioned at the peak and run it down to your room with your dryer or water heater. For a clothes dryer just simply attatch it to where your gas heat normall comes from and add a fan to draw the warm air into the dryver. I am not sure how you would use ut with your water heater..
The temp in your attic exceeds 140 degrees on average which is warmer then most water heaters and plenty hot enough to dry clothes.
You could put the clothes dryer air intake in the attic so that it draws in air that is already hot, instead of air-conditioned indoor air. Maybe then the dryer would use less gas or electricity for heat.
Living in Japan, I am a changed man. I will NEVER use a clothes dryer again. My fiance has a shirt that they (she and her sisters) have been wearing for over 15 years. OVER 15 YEARS. It looks the exact same as the day they bought it. No cracking of the paint on the shirt whatsoever. They wear it probably about 200 days out of the year, and wash it very frequently.
So, you save the environment, save money, and save your clothes. Clothes dryers are a lose-lose-lose situation.
solar hot water panals on your roof would get your water even hotter and collect that heat befor it got to your attic, they also have the possiblity of heating enough water that after your domestic hot water is hot, the extra heat can be used to heat your living space, or hot tub, or whatever.
drawing hot air from your attic for yoru drier sounds like a good idea if your drier has a thermostat that is sensitive enough to prevent it from over heating, and I hope that it would, but if it doesn't then you are just getting your drier that much hotter/closer to starting on fire, so I would start out by calling a repair center and ask them if this is a fire danger, then get a good air filter to prevent dust build up on the heating eliment.