Hi, I see that your camera is on a rolling tripod. Is the subject moving?
I'm not sure why you'd use that particular receiver (Senn EW-500).
Isn't that an 8 x 8 inch, 2 plus pounds unit? I wouldn't attach anything like that to an EX1.
Do your dolly wheels have an accessory plate in the middle? If they are heavy duty dolly wheels you can probably attach an accessory plate and then place the receiver on the plate and use longer audio cable. Also, if the camera isn't moving, (or not moving much), you cam place the receiver on solid ground and use a longer (20'...) audio cable... Or rig a sturdy bag to saddle the tripod that will carry the receiver.
Of course, you can just go with a Sennheiser G3 ENG system if you want to attach the receiver to your camera, (I attach audio receivers to the rear shoe on the EX1).
here's a link to the Sennheiser G3 ENG system:
http://www.bhphotovideo.com/c/product/618735-REG/Sennheiser_EW100ENGG3_A_Ev...