Remote features wont be possible unless accessed via IPv6...  As you said, these HT2000w units can't be put into a bridged mode, so chances are the UniFi Cloud Key will be useless for remote administration after you add on the fact you are behind CGN...

I have yet to run into a scenario where Ubiquiti AP's require a Unifi Gateway or Edge Router unless you are attempting to make remote management of the equipment and network easier, which again, is useless thanks to CGN, unless you can figure out something with IPv6...

@pswired and @tracerrx have been working together on their IPv6 conundrum together, the thread they are discussing remote IPv6 address in could provide some good insight in that area... https://community.hughesnet.com/t5/Tech-Support/HT2000W-IPv6-inbound-services/m-p/83342#M58814

To be fairly honest, I would just go HT2000w > Switch > AP's, disable the HT2000w wifi, and create my own wifi network.  Never really touched their switches or anything else as the features are mostly useless IMO.