I have had a very tough time playing AK on even the lieutenant level and I have much experience with the Panzer Corp series at that level. If you play AK as sergeant game play is a total wipe--plenty of prestige points to upgrade even auxiliary units. On lieutenant level every scenario is a battle with razor thin margins for error, often times not having enough prestige to fully replete units or upgrade them between battles. Like you say, WAY too many enemy units at Gazala for example--tanks, air units, etc. Something is wrong with the play balance. I can FORGET about more challenging levels.
Consider fixing the inflexibility of difficulty levels, i.e. allow one to advance at the BATTLE level to move up difficulty level. Or, after every so many battles employ a pop-up screen offering "promotion" as a way to increase difficulty level (or vice versa down-grade a level for a difficult scenario).
And while I'm at it--NEEDED FIXES--again, no indicator on unit hex image to distinguish heroes and medals--one has to right-click. And, when one does right-click to bring up unit details the unit data should CHANGE to reflect all the "+3 defense" and "+2 spotting" or "+1 attack" awards. A brand new purchased unit appears to have the same capabilities as a very veteran unit.
Next, I see no way to purchase new Italian units--not that anyone would want to. The next new campaign I play I may try killing off the Italian core units and replace them with inexperienced German units for the long term.
Next, is the annoying problem of deselecting an air unit. You can cancel by right-clicking an unmoved air unit that is by itself in a hex. You can do the same if there is an unmoved ground unit in the same square as the air unit. BUT, if there is an unmoved air unit in a hex and you just did something with the ground unit (ex. artillery fires) and click on another hex such as to move another unit) the unmoved air unit will be selected erroneously and move to the newly selected hex. This should be fixed--not only is it annoying but you may not be able to undo the move if a new enemy unit was spotted--very bad if you are out of fuel! One has to move the arrow cursor to an off map hex to right click your way out of the error.
Consider allowing the computer to allow variability in battle specifics when restarting a new campaign--more or less units, different locations, varying arrival times, etc.,--to make it worth replaying campaigns (and decrease the cheat tendency!). It was a very nice touch that you added unexpected reinforcements, bonus points and changed objectives!
Consider adding a mobile leader unit--for example--a Rommel unit to help the weak Italian infantry through minefields or aid the "Dash to the Wire", etc.,...for the very difficult scenarios.