Allen,
I agree with Lazz that 10' spacing is too normally close except maybe for a naturally small citrus such as Satsuma or Kumquat on Flying Dragon. Even then it is close for most purposes.
That said, in on the property behind my nursery there is a row of Calamondins (there is also one seedling grapefruit and a tangerine in the row). The trees were planted 6' or 7' apart, if that far. I would guess they are 15 years old, maybe a little older. They now form a solid hedge around 25' high. (That is a 6' fence.) The calamondins are healthy and very ornmental when the fruit is colored, which is from November until June most years.
If you look carefully, you can pick out the grapefruit by it's darker leaves and fruit.
I have also seen Nagamia Kumquat planted to form a hedge in both Florida and Louisiana, but it seems like they were spaced abouth 10" apart, maybe more.
Ned