MPP *is* "a well known patch that fixes the plethora of scripting errors and provides common-sense bug-fixes". There's no other patch this exhaustive and there probably won't be. If there's a bug that you believe should be fixed, and the patch doesn't do it, it means one of two things - either it didn't attract anyone's attention before, including multiple players, so you just have to be the first and mention it in their WIP thread, or it was discussed and decided that this particular bug should *not* be fixed for some reason, and then you're out of luck.
And what do you mean by "not having scripting on the beds"? All beds have standard scripting. Renting is done through *doors*, and since there's neither an unique door in End of the World Renter Rooms, nor in a list of doors whatsoever, nor an unique script for such a door if it existed, it was probably decided that having beds for free in Dagon Fel was intended by Bethesda and should not be fixed.