I understand where you are coming from, Those are the same things I went thru.
I happened to come across a guy selling a few year old trailer that had just been sitting in his back yard for $900, I jumped on it, paid in full in about 30 min from seeing the post, the good ones go really fast. It didnt really need anything, just needed a going thru but was good to go. It also had two spares and an M8000 bolted to it that made it's way to the front of my rig.
I have the plan to upgrade my axles at some point to haul more, I am about 500Lbs off from max, that to me is maxed out. I know it may need a little more structure too but as I really wont have much more than a 5000lbs rig on it it will be just overkill.