I like this a lot. I remember that when my dad taught chess he would do variations with set ups similar to this. Usually, it was for endgame, though he did like to deprive the board of rooks, occasionally the bishops, and especially the queen. While middlegame has too many permutations for just one variant to hone, I think your idea of practicing the middlegame with variants is very helpful.
Tactical Variant

"your main endgame firearms have been removed!"
Those are the rooks my friend.
Only if those are the only pieces on the board my friend.
Chess knowledge =/= Chess Skill
And my corrospondence rating is so low because I never play corrospondence, and my live rating is so low for several reasons:
I try new (most wild silly and crazy) strategies on live
I resign as soon as I make the slightest blunder, I have a problem where I can't stand to play that game once i've blundered.

Yep chess knowledge isn't the same as chess ability, after all it isn't good learning a lot if you don't apply the knowledge you have in your games

Chess knowledge =/= Chess Skill
And my corrospondence rating is so low because I never play corrospondence, and my live rating is so low for several reasons:
I try new (most wild silly and crazy) strategies on live
I resign as soon as I make the slightest blunder, I have a problem where I can't stand to play that game once i've blundered.
So basically blah blah blah..insert excuse blah blah blah more excuses..
Here is a variant I thought up that favors tactical play in the middlegame, as your main endgame firearms have been removed!