I have seen people use the trailers you mentioned behind wings. In fact, I think those are the platform that some use to mount roof mount carriers on for their trailers.
The suspension is a bit stiff on them, but for hauling tools and a ladder, thats not a huge issue.
My only concern is the beating that the bike frame takes from a trailer with harsh suspension, but there just isn't a lot that can be done about that other than maybe removing leafs from the springs, if they are multi leaf. But then you lose load capacity too.

There are a lot of folks pulling these trailers and I have not seen a lot of reported issues, so my concerns may be not such a big deal. I would just try to use a hitch like a Bustec that attaches to multiple points of the frame rather than just the saddlebag subframes.

I used a 35" x 55" HF trailer as the basis for my cargo trailer. I took two springs out so it only has the one main spring. That and lower the tire pressure to the mid twenties works perfect for my setup. That and replacing the "grease" before assembly.

I have not dealt with one of these personally, but have read several different owners make the same suggestion mmartin_tdc just made. You might consider weighing the tools you will be pulling, along with the materials you use for the bed, and compare these weights with the rating on the trailer. This may give you some insight into the weight you plan on carrying compared to what the trailer is rated for. You can remove leafs and replace them, if it is too soft. Everyone who has ever mentioned the trailer always mentioned cleaning out the factory grease and repack the bearings with a good quality grease. The bearing life is reported to be much better by doing so. As to the hitch, I am on my second bike with a hitch, and did not hesitate to pick another Bushtec. If you check craigslist, you will likely find a recent trike conversion owner selling a used one for $100-$150. If there are some shops around you that do a lot of trike conversions, they are also a great place to find a good deal on a hitch. The only problem with doing this is you will have to download the instructions from the internet, and go to Lowes/Home D for the 2 long bolts that go in the top mount of the frame. They are, I think, 8mm.