Is there any company that makes a box or a mount for a toolbox for an I-beam trailer frame? I don't have room on the tongue. My internet searches haven't turned up anything.

most of the time they are either submerged, full of water or in the way at the ramp..just sayin

You can make it work with U-bolts. Best thing to do is contact a local 4x4 shop that can make custom U-bolts (for suspensions). Or you could make your own with all-thread and a piece of aluminum.

But yes, you do want them as far forward and a high on the trailer as possible. I've had my boxes full of water before due to launching/retrieving on crappy boat ramps, and it's a giant PITFA.

Yea I hear ya on the issues with them. I had mounted one on my previous boats trailer using J clamps and reinforcing the mounting points on the box itself. Was hoping there was something specificlly made for an I beam. Thanks for the input.

I always get water in my trailer box. I started putting stuff in those small trashcans like in your office cubicles. Keeps chit dry and drilled a couple extra holes in bottom of box to drain out. fast.

Figured I'd update this thread with my solution incase anyone else ever needs a way.
I bought two trailer fender steps , mounted with U bolts and a underbody tool box. Through bolted the box to the steps, sealing up the holes with 4200. Mounted the box with the opening on top to keep it from flooding. So far so good.

The end result

Mine's mounted laterally across where your longitudinal I-beams meet the galvanized member that attaches to the tongue. This way if the keel drifts offline it won't hit the box where you have it mounted.

I get what you're saying. Unfortunately my tongue has no room for the box. Hitting the box would only be an issue if the trailer is too deep. The bow bunks will grab the boat before it gets where the box is and I have the guide posts to keep the boat in line.