Create A Stat_Density_2D Plot By Binning Fill Variable

Question

I have been trying to create a density plot in R that looks similar to the picture below.

In my code below, I have created a stat_density_2D plot that successfully plots my data, however, it fails to recognize my fill variable (in this case exitspeed) and only plots one color.

Upon further research, I believe the reason for this is because stat_density_2d bins the fill into levels. The problem I am having is that my fill variable has multiple values for the points within a particular level ultimately resulting in a density plot that only displays one color. Does anyone know how to bin my data so that my density plot can recognize the fill variable (exitspeed)? Please see below for the dataset and R code. Thanks in advance!

Data:

structure(list(platelocheight = c(2.594, 3.803, 3.254, 3.599, 
3.617, 3.297, 2.093, 3.611, 2.842, 3.316, 2.872, 3.228, 3.633, 
4.28, 3.309, 2.8, 2.632, 3.754, 2.207, 3.604, 3.443, 2.188, 3.452, 
2.553, 3.382, 3.067, 2.986, 2.785, 2.567, 3.804), platelocside = c(0.059, 
-1.596, -0.65, -0.782, -0.301, -0.104, 0.057, -0.807, 0.003, 
1.661, 0.088, -0.32, -1.115, -0.146, -0.364, -0.952, 0.254, 0.109, 
-0.671, -0.803, -0.212, -0.069, -0.09, -0.472, 0.434, 0.337, 
0.723, 0.508, -0.197, -0.635), exitspeed = c(69.891, 73.352, 
83.942, 85.67, 79.454, 85.277, 81.078, 73.573, 77.272, 59.263, 
97.343, 91.436, 76.264, 83.479, 47.576, 84.13, 60.475, 61.093, 
84.54, 69.959, 88.729, 88.019, 82.18, 83.684, 86.296, 90.605, 
79.945, 59.899, 62.522, 77.75)), .Names = c("platelocheight", 
"platelocside", "exitspeed"), row.names = c(NA, 30L), class = "data.frame")

R-Code:

library(RODBC)
library(ggplot2)


con=odbcConnect('username',uid='userid', pwd = 'password')

df=sqlQuery(con,"select platelocheight, platelocside, exitspeed from tm_sample where pitchcall='InPlay' 
            and exitspeed is not null")

topKzone <- 3.5
botKzone <- 1.6
inKzone <- -0.95
outKzone <- 0.95
kZone <- data.frame(
  x=c(inKzone, inKzone, outKzone, outKzone, inKzone),
  y=c(botKzone, topKzone, topKzone, botKzone, botKzone)
)

df$h <- round(df$platelocheight)
df$s <- round(df$platelocside)
df$es<- round(df$exitspeed)

ggplot(kZone, aes(x,y)) +
  stat_density_2d(data=df, aes(x=s, y=h, fill=es),geom="polygon") +
  scale_fill_distiller(palette = "Spectral") +
  geom_path(lwd=1.5, col="black") +
  coord_fixed()