If you put some hay in a corner of the box, it may encourage him to hang out there munching as well as using it. That way, he may drop more poos in the box than out.

Personally, I got very adept at whisking up poopies off the floor/rug without breaking stride.

i was having a similar issue. the issue: the hay trough was accessible form both litterboxes, but also from the floor of the pen. they’d sit in front of it and poop. i moved the hay so they could only eat hay while sitting inside the litterbox and that worked immediately. it aslo served to “catch” any hay that they would dig out. is he leaving piles, or might they be ones that get kicked out at random? in my pen, there are always some poops on the floor that are from them hopping in and out constantly. your best friend will be a cordless hand vac. whip it out, suck ’em up… it’ll only take a few seconds.

and be thankful it’s not pee. lol…

Ditto that, no problem scooping a few stray poops here and there, but yuck if they miss the box with pee!

this is how i had the hay before.  and this is how they ate it.

now i have the two litterboxes pushed together, the hay box is secured in the corner of the pen over the red box.  so they have to either sit in the red box or in the blue box to reach…

or… might you need a larger litterbox?  does he have room to stretch out in it?  i used to use the triangle corner box for Meadow, now we have the medium size cat boxes and i like them so much better!

Keep the hay in the litterbox on top of the litter!! that’s what I do, because bunnies like to poop while they chew hay. It took me less than one day to litter train my rabbit this way.