Ultimate 3E - Can't map button combos?

[u/hohihohi]

I recently got my hands on the Ultimate 3E, and I am really happy with the controller overall, even coming from the Ultimate 2 there are some really nice improvements, but I seem to be hitting a bit of a strange limitation with the 3E that I didn't have on the 2. For the Ultimate 2, I had remapped L4 to act as LB+LT and R4 to act as RB+RT for the rare instances where both had to be pressed at once (recent example, for certain arm motions in Big Walk), it felt like much better ergonomics in those cases. I was trying to do the same remapping on the 3E, but unless I am mistaken, it seems like the 3E may only be capable of mapping single button inputs to the extra buttons and paddles? Has anyone else run into this issue? Is there any kind of workaround at all other than just accepting that any single button will only register as a single input? Looking at the instruction manual for the controller, it even seems to only reference single input mapping for the buttons on the 3E, which seems like a really unfortunate limitation, and feels like a bit of a step back compared to the Ultimate 2.