If there is room, lengthwise, the 1025 should work. One suggestion is to use a 1/8" drill bit, spun by hand, to countersink the hole in the box, then use a flathead screw. If the 1015s still come with flathead screws, one of those should work fine.
If MT would make a 1015 box as thin as the 1025s, it would look much better under cars. There's no reason they can't.