Good job Sean. In the long run you'll be happy they are welded.
As for the shock plates you might be fine without shocks for your coming trip. Like you said it's like you didn't have them anyways. Your trailer is heavy and sees some rough roads so it would be something I would ad. Making plates with a shock eye is an easy project anyway so it won't set you back much coin or time. Plus you have time so you can experiment with different lengths. If your pack is pretty stiff you could take out some leaves to give it some flex and take full advantage of having suspension (leaves and shocks).