Long supply line and capacitor to prevent voltage drop
You need to treat the line as an in series inductor. 

This may be the limit of lumped element mode analysis(treating the line as a simple inductor is an example of this), but it will at minimum give you a good starting point.

The line has two values, an inductance and a capacitance, if you place the supply entering an inductor, then a capacitor from the line in parallel with your capacitor it should work quite well.

There are many tools for calculating your inductance, I quickly turned up this one.

Since you are putting a large capacitance at the end it will probably be so large in comparison to the capacitance of the line that the line capacitance is negligible.