Multiple objects with constant acceleration There are a number of formulas involving acceleration at http://math.ucr.edu/home/baez/physics/Relativity/SR/Rocket/rocket.html. These formulas all assume that, at time 0, the origins of the rest frame and accelerated frame are co-located.
The cited reference talks in terms of rockets, so I'll adopt the same terminology. In those terms, the formulas assume the rest observer's location is the same location from which the rocket departs and that time 0 is when the rocket begins accelerating from a starting velocity of 0.
Let's place another rocket some distance away and let's have it begin accelerating at the same rate and starting at the same time. Any mention of simultaneity is suspect, but we start with everything at rest, so all clocks are synchronized.
Once the rockets depart, rocket time (as seen by the rest observer) depends on the distance from the observer. With the formulas, given any t, I can calculate the corresponding T for the rocket that leaves from the observer's location, but I have no idea how to correctly calculate the time for the rocket that begins its trip some distance away.
Trying to reason a solution gets me more confused. Let's say we have three colinear locations, X1, X2 and X3, where the distance from X1 to X2 is the same as the distance from X2 to X3. We place rocket R1 at X1 and R2 at X2. The rockets depart simultaneously at the same constant acceleration, R1 headed to X2 and R2 to X3.
Observers at X1 an X2, being at rest with respect to each other, will calculate the same travel time for their respective rocket. X2 will expect to see R1 at the same time that X3 sees R2.
R1 and R2 do not decelerate. When they reach their respective targets, they are moving at some high velocity v. Because R1 and R2 always share the same instantaneous inertial frame, they always perceive the distance between them as invariant and their clocks should remain synchronized (from their perspective).
If observers at X1, X2, and X3 see length contraction for R1 and R2, it would seem that R1 and R2 could never simultaneous reach X2 and X3, despite the calculations. If they do reach X2 and X3 simultaneously, then the distance between them should appear to observers on the rockets to be greater than their initial separation.
As is usual with these things, it's probably a simultaneity confusion on my part. It seems that the rockets must arrive at the same time from the point of view of X2 and X3, but then I could make the same argument if I flip the rest frame and accelerating frame: the rockets also believe they arrive at the same time.
Any insight appreciated.
 A: 
Once the rockets depart, rocket time (as seen by the rest observer) depends on the distance from the observer. With the formulas, given any t, I can calculate the corresponding T for the rocket that leaves from the observer's location, but I have no idea how to correctly calculate the time for the rocket that begins its trip some distance away.

None of the formulas on the linked page depend on the location of the observer. You can translate the starting point of either the rocket or the observer freely. 
Note, those formulas do not describe the visual appearance of what images the observer actually visually sees. They describe what the observer determines actually happened after correcting for delays due to the speed of light. This is the reason that the formulas do not depend on the location of either the rocket or the observer. 

Because R1 and R2 always share the same instantaneous inertial frame, they always perceive the distance between them as invariant and their clocks should remain synchronized (from their perspective).

This is not correct. This is essentially the mistake that is often made in incorrectly analyzing Bells spaceship paradox. The distance between them increases in their respective Rindler frames. 
