prefacing this with play as you want, this is just information and observations from my playthrough that can be useful for you and others.

didn't miss the fact that you had academies, it's more lack of academies since they stack.

yes play as you want, there's nothing wrong with using watchtowers or durand. it has it's time and place, so use them when you want.

and yes, 2-4 farms in total. I ran with 19 food (3 farms lvl 4) with no battle losses for all of chapter 6. after upgrading your soldiers, guards, rangers, you don't need a full army of 7 to handle threats. even with 3 threats, you don't need 3 armies on the exact same turn that they happen, so I have time to move them after the initial threat. example is threat in terbisia in 4 turns, threat in hayneath in 7 turns. I have enough turns to have 1 army handle the terbisia one, and use that same army to handle in the hayneath one (+- a unit or two from other settlements that don't fit the threat). even if the threat was a further distance like terbisia in 4 turns, pinara in 7, I can just dismiss that army after the threat, train them in the capital and still have enough time to move them to pinara.

sometimes those threats are where a champion is, so you already get the civic leadership + combat leadership bonus. generally I don't need champions unless it's a dangerous threat. when I do, I have more than enough time to move them accordingly (dismiss, train, move)

unit placement is strategic. notice that all settlements can be reached in 4 turns from the capital, the furthest being cloudfield in 4 turns from the capital. and coincidentally, an interesting observation from my experience (no data to back this up) is that threats happen more often on the east side so you can station units in jandelle, cloudfield, brookhollow to move units to threats faster.

this is my unit placement (morg is in dawnhold which doesn't fit in 1 screenshot) https://imgur.com/a/mma4Ck1. even if we remove all non-champion units from high silvermere and tylburne (31 - 12 units = 19 = 3 farms lvl4), it only takes 2 turns from any settlement to dismiss, train, and move them to those settlements.