I've spent more time then I care to admit, attempting to change caps to backspace in Lubuntu on a spare computer (15.10), cause I want to switch to lubuntu as my main linux (with 16.04). Basically once you have got used to using caps as backspace you have ruined your ability to use normal computers. I don't recommend it, but I wouldn't go back. Here is what I have tried based on less detailed answers.
$ sudo setxkbmap -option caps:backspace
also tried editing /etc/default/keyboard to have the same option
also tried to add it to the options field in the keyboard switcher panel
Logged out and in testing before and after even adding the setxkbmap line to startup and restarting
Is there a guide somewhere on the exact syntax of using setxkbmap? The man goes over options but doesn't show syntax for various keymappings, the main guide link is broken
Is there a more reliable way (maybe simple graphical way) to do this other than setxkbmap?