Wow! The trailer is great. You could pull it behind a golf cart, of course.
Yes, you're right about most filter coffee machines. The water hits the coffee at about 75°C and gives an inadequate extraction, usually watery, bitter and sour all at once.
There are other machines, however. The Technivorm Moccamaster (Dutch) is available in a number of configurations with glass jug or vacuum flask and makes an excellent brew. They are hand built and in the Netherlands and are still quite affordable, if not exactly cheap.
Steve mentioned another good filter machine recently, but I forgot the name.
You can use paper filters or a permanent gold filter if you think the paper somehow detracts from the coffee.
Alternatively, a simple Melitta pour-over filter with paper or gold filter does an excellent job, assuming you don't mind using a kettle and hand pouring the water.
Good luck.