Certainly I have a TL-WR1043ND-V2 running Gargoyle with a USB 3G Huawei E160E. The D-Link DIR-835 should also work with 3G USB.
Yes Gargoyle can be upgraded on all routers so long as there is sufficient Flash and Memory for the new version.
Can you help someone else get Gargoyle up and running? TL-WDR3600 : Gargoyle 1.9.0 : NBN FixedWireless
TL-WR1043ND-V2 : Gargoyle 1.8.0 : 3G Huawei E160E