We just built our first raised beds for an SFG. They are 4'X 8' with 12" high wood sides and 4x4 posts on the inside corners. The posts extend 1 foot from the bottom of the bed for sinking in. This weekend we're digging them in and adding a trellis to the north side of each bed. Can I just sink 8' t-posts in the same holes as the 4X4's and then mount them to the inside of the wood sides and stretch nylon trellis net between? Do I have to have a top bar of some kind? If so, what should I use? We've already put a fair amount of time and money into the beds themselves and the whole plumbing pipe/conduit plan baffles me. This sounds easier but I don't want to build something that won't hold up. This is my first SFG and I really want it to be successful!