Just a wild guess but, if you put something solid in there it would be bouncing on the wires to the ECU.
Probably not good for the longevity of the ECU.
Yes, I do agree, but i was specifically thinking of just a small power distro box and fuse that would screw into the side, letting it be close to the battery and putting my registration and insurance papers there which I probably never need to get out, but then I have them in case I ever get pulled over (which has never happened, but I should have them). Figured it was perfect for that, and sounds like it is. I do get it now, I was trying to figure out if there was something there I just didn't realize (like if it was a catch drain for bed channels or something, which makes no sense, I just couldn't figure out what it could be- but that makes sense just to protect the ECU wires)
Under hood I already have a box, I was just thinking about ordering the glove box and wanted to make sure I didn't have an issue. under the hood, as when you order they make a point that it fits with the OEM under hood box and I wanted to assure that also didn't mean it "only fit with the OEM box and not other boxes". I don't keep stuff I regularly need under the hood since I have to take the windshield off to get it, its more of the "oh sh*t your stranded" type of stuff because I use mine on a farm by myself and need to be able to save myself if I get in a bind far away from others, so spare fuses, emergency tie downs, Less necessary tools (Sockets, wrench sets, tire repair kit, zip ties, spare electrical, tire inflator, radiator stop leak, oil, coolant, spare plug), first aid kit)
Space under the drivers seat is kind of a PITA with the rubber cover (clearly honda engineers WANTED to make it useless so you felt compelled to pay $200 for a storage cubby)- I may but a storage place or may work on hacking something together one of these weekends.
The bed I want to leave open because while I may take it to trails occasionally, I do more farm work on a mountain, and don't want to take up precious bed space or not have that emergency stuff when I need it, despite the fact it adds weight- I am installing a jump seat for when I need to bring people from point A to point B on the farm at 10 MPH on flat land, and then pop it off and use the bed for doing work, and then pop that off and strap in a larger rear box for when doing offroad trails and I want more water tight storage for more gear and extra fuel and stuff. All in all its a good setup to try to do "everything", despite trying to do everything means you do nothing perfectly.