The AC130 is not, has not, and will never be a bomber. Again, you are comparing aircraft designed for two distinctly different roles.
That last image has it loving bolted to the ground. are you blind? In the time it takes to get that thing set up, the enemy will have laughed themselves to death.
I've already addressed the first point, but I'll do it one more time just so we're clear:
Oh my
I'm so damn sorry
everyone stop everything
I put a loving A in front of C-130 by force of habit
AC-130s don't drop bombs. -

That's a link, by the way. Clicking it will get you the full size, just so you can read the part where it says "C-130" and then read the word "bomb"
part 2:
I'm not blind, you're assuming it's bolted. The size is significantly smaller, and that rig appears attached to the tank. In my eyes, it appears to be a system where the tank is stopped, an arm folds down, locks into place, and then secures to the ground. Unless you have documentation on that specific blueprint that says it is bolted to the ground, no.
Also, in terms of the set-up time... Set it up before enemies get there? It's for howitzers, they're not SUPPOSED to be that close to the enemy. Get it ready, fire away, when they find you, take it apart and ship out. Not a hard concept. It's the same as any other howitzer setup.