are you making it out of pvc for weight and transportability i suppose?
because i just get wooden branches and bolt them with SS bolts. Its much more straightforward and sturdy in my mind.
...umm... those circle things that you can tighten around the joints... i forget what they are called. basically a loop that can thread through a screwy end and you tighten the screw and the loop becomes smaller and smaller...?
but i was only considering them as it will be covered in rope and inaccessible (because i don't think they are made with safe metals).
sorry i wasn't much help. but i think if you don't let it ooze outside the T-joint glue should be okay: with a little discretion put on keeping an eye on whether they do in fact chew and break it. in which case i would remove it anyway because broken plastic can be sharp.