I, for one, am not a fan of the multiple missions in 1 mission thing. Of course, you're always free to do as you wish ;D.
What I'd try here, is to break it down into separate missions, maybe make a little mission pack for them. That way, you could focus on each part much better, rather than worrying about the entire string of events that will happen.
Defend camp and retreat:
Paratroopers and choppers are a good way of saying "Get the heck out of here, and we mean it!" And I like defensive positions to be reinforced with static defenses, like MG's guard towers, sand bags, etc. (Set up like you really wanna defend it)
Defend town:
Same kind of idea here with defense setup. One thing I think makes a defensive mission better is "waves" of attack, rather than one onslaught. This way it kind of keeps you on your toes, even though you think you've won.
Attack Base:
Attacks are always better when it's a collaboration of squads and groups, rather than 1 squad hitting the base head-on. Different elements such as mechanized inf, APCs, tanks, and infantry each add their own unique things to a mission. I like it when a mission designer tries to make variety in the mission by using different elements for their own specific tasks. Of course, they'd all be working for a common goal: Kill the Reds! ;D