Do you just channel the tiles behind the targets?
Behind, to the side, and between the ranges. It's not the best example, but you can see it in practice
here.
Here I've fit it into a smaller space, an even number of tiles wide, which is just one of the points of inefficiency. (Another being that it is well away from the surface, so not a convenient muster-point.) For symmetric reasons, alone, I will be putting similar ranges in each of the other three orthogonals away from the centre if this fortress last long enough and I have "miner time" to spare. You'll note that I went into the cavern layer, with the most southerly extents, and so instead of smoothing the natural rock I built the walls and floors out of blocks of the right material. (Indistinguishable from normal smoothed stone, blocks of an identical colour and indeed just raw-stone wall/floor, but just for my own delight and delectation.)
My more typical layout is more something like:
+#...#+++++++++++#...#+
##...#############...##
.......................
...X...............X...
.......................
##...#############...##
+#...# #...#+
+#...# X X X X X #...#+
+#...# + + + + + #...#+
+#...# + + + + + #...#+
+#...# + + + + + #...#+
+#...# + + + + + #...#+
+#...# + + + + + #...#+
+#...# + + + + + #...#+
+#...# + + + + + #...#+
+#...# + + + + + #...#+
+#...# + + + + + #...#+
##...# + + + + + #...##
.....# + + + + + #.....
...X.# + + + + + #.X...
.....# + + + + + #.....
##...# + + + + + #...##
+#...# + + + + + #...#+
+#...# + + + + + #...#+
+#...# + + + + + #...#+
+#...# + + + + + #...#+
+#...# + + + + + #...#+
+#...# + + + + + #...#+
+#...# + + + + + #...#+
+#...# + + + + + #...#+
+#...# + + + + + #...#+
+#...# + + + + + #...#+
+#...#>+>+>+>+>+>#...#+
##...##+#+#+#+#+##...##
.......................
...X...............X...
.......................
##...#############...##
+#...#+++++++++++#...#+
Functionally, "." and "+" represents only the difference between corridor floors and 'room' floors. "#" is regular walls (usually undug, often smoothed) and ">" and "X" the downwards stairs and archery targets (not up/down stairs) exactly as they'd appear. Spaces are channels. Denuded of ramps on the level below (or prevented being so by pre-mining through the Z-1 layer). Though I might leave
some ramps, as well as cut the down-stairs and up-stair partners, each ramp just causes problems with the stockpile. Occasionally (especially if I've hit ores or something else precious) I might undermine (with impunity) the range-floor as well, for more stockpile space.
In this case, this layout crossing two of my 'roomblocks', and interrupts one of my usual corridors. The actual longest range distance is slightly longer than I've given here, though, and I may extend it to three-roomblocks'-worth, or five-blocks-worth to fit two back-to-back ranges extending across approx 2.5 roomblocks.
The level below is all/part bolt stockpile. (Few or no bins to be used. There's enough space for them.) I also tend to smooth all the stone through which this is built. Another aesthetics-only aspect, that.
I've often used an even wider spread, with dozens and dozens of ranges. Either because I have loads of marksdwarfs, of because I intended to be ready for them.