How is your axle attached?
is it bolted or welded, is it on leaf springs or torsion arms?
I changed the axle on my Trillium
by myself, it took about 6 hours start to finish, jack the trailer up, block it with safety stands, take the wheels off, lower the rear spring mount (leaf springs) cut the old u bolts off (don't bother trying to save u-bolts),disconnect brake wires, roll the old axle out, roll the new one in finger tight the u bolts, re hang the springs, connect the brakes
, torque everything to spec, re-mount wheels, lower trailer, torque wheels, and drive away.
If you are going to do it yourself, measure everything about 10 times, draw a picture and re-measure, put all the measurements on the drawing and give a copy to whoever you get to build the new axle.