Okay, I apologize for not being able to get back to you sooner but I have some good information for you now.
Because you are running on 5ghz, you should check if "ieee80211h=1" is required in your country. This command enables DFS and radar detection to avoid interference with radar systems. If you are unsure you should add it to be safe. If you switch to 2.4ghz you no longer need this, it is only for the 5ghz band. (It appears this may not work with all drivers, so if you find this to crash your hostapd just ignore it.
I also recommend you set "ieee80211w=" to either 1 or 2. When this is enabled it prevents someone else from using a deauthenticating attack your connection (disconnecting you) from your AP. Deauthentication is a known method to use by hackers to cause a MITM attack. More importantly, if someone was playing with you it could result in possible crashing (loss of control or video) or them taking over your drone in an extreme case.
For good practice also use "wpa_pairwise=CCMP TKIP" this will try to use AES (much stronger) instead, but will revert to TKIP if there is a compatibility issue. Otherwise, your rsn and wpa look properly configured for AES which is much more secure and supposedly gives better network performance and speed.
"ieee80211n" should remain as it will help you achieve higher range. This may seem contradictory as usually lower bandwidth results in shorter range and you will find that most forums will agree with this general concept. However, 802.11n does much more than increase bandwidth which should theoretically improve performance. It even includes MIMO (diversity) which definitely helps range, although unfortunately in your case your wireless adapter does not have diversity.
You should get rid of "ieee80211ac=1" as it is not supported by your wireless card anyways. In theory, if you were continuing to use 5ghz and your card supported AC wifi, you should enable this for similar reasons as above. In fact AC supports a new kind of MIMO which slightly increases performance in that field of things. Do note that AC does require modification to achieve range though as it is very high bandwidth and low range by default. I am simply stating that when properly modified it could increase performance.
"HT-Capa" would increase your range. This is the modification that can be used on 802.11n and especially 802.11AC as I mentioned to increase range. However, you actually want to use this to decrease range. While wireless n and ac add many features as I said above they also increase the width of the network channel. For instance 802.11n increases the channel from the standard 20mhz to 40mhz. In doing this it increases the bandwidth but decreases the range of where the radio power is concentrated (therefor decreasing range).
It appears by default this is enabled: "ht_capab=[HT40-][SHORT-GI-20][SHORT-GI-40]" though it is unclear and it now appears it may automatically be set to only 20mhz. In either case for good practice set "ht_capab=[SHORT-GI-20]" this should give you the most range. Allowing you the higher range of wireless a/g while allowing you all the improved features (security, latency, etc.) of wireless n.
There are likely many more modifications you can make under the hostapd wireless n settings though you would have to google and experiment. I myself will be looking into this more as I work on my blog site. Currently, don't have time to do everything as I can only really focus on one thing at a time, and that is getting my website up
Wireless card output power. As I said before do to lack of any other info I will assume your cards max power is 500mw.
I have no clue what the regulations are in Australia and would help but I cannot find any solid info. In any case you must realize that you need to check the maximum allowed power in your transmitting channel for your country.
First type "ifconfig" and check to ensure that your wireless card (I assume wlan1 is your AP) reports “Power Management:off”. If it does not adding this line below (wlan1) in your network interfaces should disable power management "wireless-power off". Which will definitely improve performance regardless of changing power.
Also search for "tx-power" by default this is usually 20dbm.
The command "iwlist" should give you the supported frequencies and power limits based on your hardware and regulations. In any case these should get 500mw working for you (if it is allowed by your country regulation, otherwise it will not work)
ifconfig wlan1 down
iw reg set AS
ifconfig wlan1 up
iwconfig wlan1 txpower 27
and check ifconfig again to see if the tx-power successfully increased. Also, the following should give you a more modest 200mw. But still two times the default output power of 100mw.
ifconfig wlan1 down
iw reg set AS
ifconfig wlan1 up
iwconfig wlan1 txpower 23
If you get any instabilities (should not occur below 1w) Increase the usb hub power from .6A to 1.2A by adding
"max_usb_current=1" here "sudo nano /boot/config.txt" This should be safe for the RPi as it is usually only disabled by default incase your power supply cannot handle the extra power. The power module is able to supply up to 2.5A I believe, maybe higher which is more then enough. I believe the RPi itself does not support above 2A or 2.4A or something.
Finally, may I ask why your "eap_reauth_period=360000000" is set to high?