This is one game I've been wanting to TAS since I first got into TASing. While perhaps it might not be immediately the most entertaining to TAS, it certainly has the difficulty to be a challenging game.
The first practical concern I have is the feasibility of skipping missions which remove Danger Zones from later missions. In a Danger Zone, enemies fire much faster than normal, take more damage to kill and do triple damage, which is a concern for the Apache's limited health points (600) and ammo. Doing Mission 1 in Map 1 for example removes the Danger Zone in Mission 3, which makes that mission notably easier.
Map 1: It is possible to skip Mission 1 entirely, and still finish the map fully. Whether this is possible or practical is another matter entirely. There will need to be an ammo refill after mission 2, and probably to pick up the ammo hidden under one of the large buildings in mission 3. The commander in mission 4 does not show up until both missions 2 and 3 are complete, and he gives you access to mission 5. It will be practical to take out the building for mission 5 on the way to the power plant, so we can immediately land on returning.
Map 2: This is one map where I would consider grabbing the quickwinch, and it is located near one of the jails so it is a short detour. Mission 1 is again another radar station mission which could be skipped, but it affects more than 1 later mission in total so it might be easier to do this. Mission 3 is again the power plant, and the armour repair might be needed here. Mission 4 is the chemical weapons plant, then onto Mission 5 for the Scuds. It might be easier to pick up the commanders first and go on a scud killing spree later, depending on location. Finally, it is the rescue of POWs, so more boring ferrying. Is it worth getting Valdez, the best co-pilot in the game? No, you get the option to pick him anyway whether you collect him or not, as I recall.
Map 3: This one will be the most fun. It might be the most practical to take out some or all of the ICBMs immediately on landing at the beach, since you're already there. For that matter, the power station is not out of the way either while doing this. I believe the speedboats in mission 4 don't appear until mission 3 is complete, so a lot of the early missions can be done before getting onto land proper. There is Mission 6 which appears after the power plant is done. Mission 7 has an unmarked radar site granting it a Danger Zone, so it might be prudent to eliminate that before entering. After all that, it is the fun of protecting the school bus. If my reckoning is right, much of the missions can be done over the sea at the start, requiring only a few things to be done on land. This has the benefit of meaning you need little fuel until the last mission.
Map 4: Ah, this is fun too. Can do missions 1 and 2 more or less together. Quickwinch is along the beach so it will be practical to get. Mission 3 is another ferry civvies to safety job. Power station should probably be done next, and this should unlock the bomb parts mission. Probably best to take out the 2 radar stations protecting the Nuclear Weapons Depot before doing Mission 6. Then it is the final stretch. It is probably quicker to get full ammo and destroy the bomber in a single ammo refuel, since you'll do a lot of quick damage with the chain gun.
Bomber has 3000 HP. You can eliminate 800 with Hellfires, another 800 with Hydras, leaving 1400 to be done with the chain gun. Chain gun can be fired at an extremely rapid rate though, so that remaining damage will go quickly.
So yeah, this is a very basic plan for this game. It will require a fair bit of planning, especially in terms of ammo and fuel, and testing of danger zone feasibility, but it will certainly make for a great TAS. I don't plan to start this yet, want to get FE6 out of the way before a new project, but getting feedback will certainly help when I do get around to this.