[KTL]

I think you're bettor of removing the hard line connected to the caliper, in order to get the caliper off. Removing the clip on the trailing arm doesn't give you the ability to move the caliper around like you need to.

You can stop the brake fluid from running out of the open line by using a length of 2x4 wood against the brake pedal and the front of the seat. Its like having someone slightly press the brake pedal for you. Pressing the brake pedal blocks the free inflow of fluid from the brake fluid reservoir and that's why the fluid won't flow when the line is open