That's a lot like asking what tools you will need over the life of your trailer. And in both cases, the clear answer is "it all depends."
Personal views follow: I fish a lot out of my trailer, and sometimes I haul baitcasting gear in case I'm going after bass or muskies or pike, sometimes spinning gear in case I'm prospecting for trout or want to catch a few panfish for supper, and I always have along a fly rod or two with flies ranging from saltwater streamers and crab imitations to tiny little dry flies for most everything from bonefish and tarpon to picky summer brown trout. But I've been doing this all my life and probably have 20 or 30 rods, each for a different purpose ...
If I were you, what I'd do is to take a little drive over to Gurnee or Bolingbrook or Portage, Indiana, where there's a Bass Pro Shop ... find a salesperson, describe in as much detail as you can what sort of fish you want to go after, where you're gonna' do that, and what time of year. Then, just hand him / her your credit card, and take their advice, spending as much money as you can tolerate! They've got good, basic gear for most any sort of fishing, and their sales folks are pretty knowledgeable. The really, best thing you can do is just to get some basic equipment and start fishing again. Pretty quickly you'll run into other folks, get new ideas about what will work for you, and then next thing you know, a bigger trailer will be in the works - just so you can have enough storage space for all your fishing gear!