Okay, back from work. What put me off in becoming an engineer was the same thing you just said: engineers get paid to plan and revise things. There may or may not be an end product in this process. Their main purpose is to take something simple, complicate it severely, then try to simplify it again. Things rarely end up as they started. Just as lawyers find problems where none exist and debate them endlessly in court, engineers dictate revisions and change plans as they see fit.
You're right when you say we can't afford to do the same things as hobbyists or homeowners. Things such as comfort level, up-front cost, lifestyle, aesthetics, and value come into play. Unlike in industry, where the entire body of work may be revisited and scrutinized for who knows how long, we have very few people to please in the process, which simplifies the whole process. The cool thing is that you can plan it yourself, do it yourself, then test it yourself. When you have something put together and working, ask the wife how she likes it. When she complains, listen and fix it up. Paint it pink or whatever. Then it's done for now.
It seems to me that you have done quite a lot of homework and know what you want to accomplish, as well as having actually accomplished a great deal. The main thing to keep in mind here is that what you're planning here is only one of these and one of those. Keep it simple. Simple works.
Doing a quick search on craigslist in your area, I found the deal of the month:
RUUD 2 TON AC
If I lived there, I would have already put this unit in my yard. Add a reversing valve, a defrost control, and a BPHE wherever (indoors or out) and start tinkering. For under $300, you could have a working test bed.