How does one actually USE such an unwieldy length of rope without getting it completely tangled up? I find everything is initially fine coiled up but once I start using it, I have a knotted mess.
I suspect anything longer than 25 to 50 feet is unmanageable. I hope someone out there has a magic bullet for me.
Climbers routinely manage 50 meter (~165 ft) or even 70 meter (~230 ft) ropes, and avoid having a "knotted mess" (usually). Likewise, sailors routinely use various methods to neatly coil the lengthy ends of halyards etc.
No real magic bullet. Just use the part you need, and neatly coil and tie off the rest. There are numerous ways to coil the unused portion. Take a look at various books on climbing or sailing. The only real magic is learning to make the coil without kinking.