Christmas tree plantation & companion plants

I have a road frontage on a fairly busy country byway, and have been thinking for some time how I might put the acre of flat grass right next to the hwy to productive use. My wife doesn't want the small ones to play next to the road, because it's too busy; nor does she want to give me free reign to build up a "disheveled looking" food forest in front of the house. So a few weeks ago I was discussing it with a friend and he said, "What about starting one of those christmas tree plantations? They should be fairly low regular labor, and you only have customers on your property when little else is growing, and the one in [a township about 8 miles away] is charging $80 for a 7 foot tree!" So I've looked into it, and I have a rep from the state ag department coming out Friday morning to discuss it with me.

But I was wondering, if I should do this, it will be at least 4-5 years before the trees are large enough to bother selling. What can I interplant in the meantime that might help trees grow, or otherwise put the gaps of mostly grass to useful purpose. And if nothing else, not having to cut the grass between the trees in summer would be useful as a labor/energy/money saving exercise.

Please advise...

I was just searching this forum for this question, so hopefully someone answers.

From what I have read, you could plant lingonberries or blueberries with evergreens.
Berries could make a nice blocker between your yard and the road.

Daffodils and Lily of the Valley will grow with evergreens.
If you check on PFAF, you can search for your hardiness zone.
Isolate your search for plants that like an acidic soil and at least partial shade.

You might be able to experiment with plants that do okay in neutral soil but they wouldn't do as well.