Jim, before you use that Dot 5 make sure your system components are compatible with Dot 5, not all are. If your trailer originally used Dot 3 then you may not be able to use Dot 5. Call the trailer mfgr. to find out. IF you can use it you have to purge as much of the old fluid as possible before adding the Dot 5, force it through a couple times before bleeding or contamination will occur.
You can make a pressure bleeder with a mityvac, clear poly hose and a rubber stopper. Check this thread at Tigéowners.com; http://www.tigeowners.com/forum/showthread.php?t=2706&highlight=bleeding+brakes
it shows how to do it. I've done it this way a few times and it's foolproof. Use light pressure when pumping or you'll blow the stopper right out of the master. It helps to have a helper when bled to hold the lever closed so you can close the bleed valve. Do the furthest one from the master first and then the other.