What if instead on relying on castle numbers/QR strat to decide the proportion of army defending, it was made as a selectable option within limits.
Say you could choose in the strategy page to defend with 25%-90% of your army, or even make it super granular to defend with certain percentages of troop types depending on the situations you are anticipating. Might want to make some downsides to defending with less, say the troops eat 50% more due to spending more time on leave or something.
That way if you think you are able to defend a hit against someone, you'd go with max army defending. Or if you know it's hopeless, you try to save as much army as possible and take the retal afterwards. Even have this detectable via a TS, something along the lines of 'It only looks like about 75% of the standing army is on guard" with the usual TS inaccuracies imposed, of course.
This could help prevent the after affects of pre/re, which were it slowed the attacks down and made it hard to cycle out top kingdoms because every hit pre-cli was almost a guarenteed army kill, except on the group that had the largest amount of players.
I don't know if adding more variations of protection is a good thing, even CLI I am dubious about. But the main purpose of protection is so you can rebuild army, so if we had a way to accomplish that goal using other methods it might be better?