Enable nginx X-ACCEL for an entire drive

I want to use X-ACCEL to speed up downloads (currently maxing out at 60-70MB/s on local network, nginx direct downloads saturate gigabit connection), but I've been unable to make it work properly.

I use Stablebit's DrivePool software to combine several large drives into one big virtual drive, D:/. I've set my user home directory as the root of D:/, this gives me access to all of the drive and I can share specific folders with friends. However, some files are quite large (50+GB).

Currently using nginx as a reverse proxy pointing to an apache2 instance running RileRun. I believe I can enable X-Accel using 

Internal; 

root d:/; or alies d:/;

but this prevents access to the web interface entirely.

Any ideas? I'm open to switching to a different reverse-proxy like Caddy if it will solve my issues.