Ok, things have been busy but I finally got a chance to try it out. I'm not getting repeated "Trust this computer" prompts on the phone anymore but in this case I don't think that's a good thing. I see two entries in Nautilus but they are inaccessible, something about a bus timeout. Here's the relevant parts from dmesg:
[2310460.848063] usb 1-5: new high-speed USB device number 3 using ehci-pci
[2310460.966237] usb 1-5: New USB device found, idVendor=05ac, idProduct=12a8
[2310460.966250] usb 1-5: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[2310460.966257] usb 1-5: Product: iPhone
[2310460.966263] usb 1-5: Manufacturer: Apple Inc.
[2310460.966268] usb 1-5: SerialNumber: fe71483062859b99f1bc5fe78ef1ab1a51bd7875
[2310461.006078] ipheth 1-5:4.2: Apple iPhone USB Ethernet device attached
[2310461.083385] systemd-udevd[21596]: renamed network interface eth0 to enp0s18f2u5c4i2
[2310461.096854] IPv6: ADDRCONF(NETDEV_UP): enp0s18f2u5c4i2: link is not ready
[2310462.524983] iphone-set-info[21579]: segfault at 0 ip (null) sp 00007fffcad6d768 error 14 in iphone-set-info[400000+3000]
[2310463.106048] pool[21611]: segfault at 0 ip (null) sp 00007fd747ffec08 error 14 in gvfsd-afc[400000+29000]
[2310464.181294] pool[21622]: segfault at 0 ip (null) sp 00007fb3275bfc08 error 14 in gvfsd-afc[400000+29000]
[2310480.380756] pool[21634]: segfault at 0 ip (null) sp 00007f5ecccdfc08 error 14 in gvfsd-afc[400000+29000]
[2310488.472159] pool[21641]: segfault at 0 ip (null) sp 00007f720a445c08 error 14 in gvfsd-afc[400000+29000]