I get what you're saying - you need it to get higher up so you can hear it.
What I'd do is add a sub to your PA, and then use a single tilt-back cab like a monitor

If you're not running bass to the PA at all, try in-ear monitors and a personal mixer - far better investment than another stack of cabs. Run a line out from your PA + your bass to the personal mixer, personal mixer out to in-ears, bass cab as "bass main."
I'm kinda weird though in that I am compulsively against having to carry two cabs

Maybe you can get don to use those clamps that lock the cabs together or something.