Is there any way to access the console logs on an iOS 8 device without installing Xcode?
Yes. Apple Configurator 2 has a command line tool that can tail and/or dump the console logs and do some other nice operations like pair, enumerate connected devices, etc...

cfgutil syslog


That's the official Apple way and it's much smaller a download than Xcode. Both are free but cfgutil is much more powerful and can do things like remove apps, erase, pair, and even run scripts when you attach and detach iOS devices to your Mac.

To make cfgutil available at the command line, open Configurator 2, and choose Configurator 2 -> Install Automation Tools ... from the menu.

You could also look at homebrew and install libimobiledevice - that is open source and free as well and seems to be kept updated fairly well over time.

brew install libimobiledevice