Here's my take on the Dave_C #NanoLongRange 1S 18650 quadcopter. Thanks to Dave for all the great work he's doing for this hobby!

I found this was actually a very interesting, but challenging build and I went through quite a few design iterations along the way and learned a lot.
Please drop a comment if you have any questions and I'll do my best to help.

Some lessons learned... I originally planned to use the ImmersionRC Tramp Nano VTX, but I blew that up before I could use it.
The voltage step-up (same that Dave_C recommended from Bangood) was faulty and was unknowingly outputting 9V instead of 5V and destroyed the Tramp VTX. I was rushing and didn't check the output voltage before connecting the VTX. I happened to have a Zeus Nano VTX on hand, so I swapped that in with the 2nd regulator I had (which was OK). I then managed to melt some components off the backup regulator when I caused a short during troubleshooting. So I flew it for a while with the VTX powered from the FC 5V and I found it worked down to almost 2.9V which gave about 12min of flight time. I then replaced with Pololu regulators and a new Tramp Nano VTX.

For the GPS connection, I reassigned UART1 (factory set for the WiFi) to the LED and S5 pins. I then reassigned UART2 RX pin to softserial TX for Tramp VTX control. (Ghost protocol uses UART2 TX pin). At first I tried the GPS via softserial, but couldn't make it work.
Here are the modified resources:

resource MOTOR 5 NONE
resource PPM 1 NONE
resource LED_STRIP 1 NONE
resource SERIAL_TX 1 A08
resource SERIAL_TX 11 A03
resource SERIAL_RX 1 B03
resource SERIAL_RX 2 NONE

Since the Ghost protocol isn't available in Betaflight 4.2, I installed the BF 4.3 development build. I used the new features in BF 4.3 to reorder the motors and to change direction. Very easy!

ESC is flashed with BLHeli_M firmware v16.9 48 kHz PWM.
Edit: after some testing, I believe flight performance and flight time are better with 24khz PWM.

The original build was about 110g without the GPS and with an XT30 soldered to the battery and mounted with a couple elastic bands (because I'm still waiting for the battery holder).
The final version is a remix of a remix... it incorporates the battery holder in the frame and all part shown below. I remixed it further to reduce weight as much as possible and managed to keep the weight at 111g with a GPS added.
I've squeezed out a maximum of 21 min of slow flight time from this build and flown 10km total distance (5km out and back):

Actual DVR of a +9km flight that was 4.5 km out:

If you just want something relaxing to cruise around with, this is a great option.
If you want something to do some medium/long range flying with, this will surprise you!