John,
As handy and smart as you are, the install will be a breeze, I raised my plug for the dryer, the original is too low. Jim's suggestion about the basement shut-off is a great one.
There are many stackable combo's out there, 120 volt dryers are as well. I like the Maytag and Whirlpool because of the parts availability where-ever you are, also If I want a Sears Tech to come Service it, they are in any town. Also, the on-line Sears parts is about the best out there. (I imagine the parts are cheaper than the RV washer-dryers as well)
The space where the vent goes is a no-brainer, just half way in the closet-wall is good. You can see the studs on a dewy morning clearly, there aren't any in that closet, IF your unit is like my 3400RL, washer closet right in the front door to the right.
Note*** I know the RV washers and dryers are made very well, do a great job and I am not knocking them, there are thousands of them in service, are reliable and people are happy with them.
Here are some residential stackables:
http://tinyurl.com/Ozzwasher
Haier dryer
http://tinyurl.com/Haierdryer
Whirlpool 120 volt dryer
http://tinyurl.com/120voltdryer