I can see where you're coming from on the distance to the ball, but after you've done it a few times it becomes second nature. You're a lot closer in that scenario than you are with a GN or 5th wheel setup as well which aren't bad either (although with the 5th wheel setup your obviously keeping the tongue at hitch height so you can lock into it, making the GN attachment being the more appropriate comparison). Unless your tool box is extending beyond the sides of the trailer you'll be fine with the 5-10k jack mounted against the front of the trailer deck frame. The caveat to make this possible is a pipe extension to the jack rod (secured to the outside of the trailer by a larger collar with either a greasable zirk or a roller-bearing setup like this:
View attachment 366157
Here the tongue has a built-in chain box (pretty lacking IMO) bu you could easily mount an angular box in it's place and have much more capacity without interfering with your ability to mount and dismount the trailer like these:
View attachment 366159 View attachment 366158 You'd just have to design the tongue opening to suit the box you want (easiest method) OR if you've already fabbed the tongue, find a box that fits your needs and dimensions. I had always envisioned mounting the box on the tongue, but looking the the 2nd pic, mounting in the tongue (as long as there's a minimum 1' ground clearance) is brilliant. I wish I'd thought of that already...