Wireless, remote speakers with Dish Hopper?

One of the best systems available for playing music in various locations is made by Sonos.
But you will require a wifi network and router in your coach for it to work. They have models that have built in amps to power your speakers, versions that have speakers built in, or versions that require separate amps and speakers.
I utilize 2 units in my coach. One for outside speakers that I hang on the side of the coach and one for the inside system. I also have a hard drive with 20,000 lossless songs in my music library. They are perfect for at home as well. Capable of playing music in 32 different locations in your home. Google Sonos. It is not the cheapest way to go but it is a proven system that allows you to control it with an app on your phone. It will even play music stored on your phone.

From my experience using BT headphones with our Hopper, I'd say that 30' maximum distance is fairly accurate depending on what's in between the hopper and the BT device.

The specs for blu tooth, say 30 ft max range
I don't use bt so I can't say how limiting that might be for your use

At home we use a Bluetooth speakers with our hopper

I don't know anything about the Hopper outputs, but have you looked at a bluetooth transmitter and a bluetooth speaker? Most BT transmitters have an input that could hook to a soundsource by mini jack or rca adapter.

Check into the Rocketfish wireless systems (Best Buy has them). Little pricy, but anything worth having is going to cost.