Well, Vray for c4d uses something between option 2 and 3 - it has a standalone version (which comes directly from chaos group) which is installed on the slave machine, and in the main machine I only put the ip of the slave machine ( I think we get up to 10 free nodes in vrayforc4d). But (and it's a big but), because the slave machine has the standalone vray that comes directly from chaos group,and not from the vray for c4d developers - I can't use any native c4d shaders or 3rd party shaders - I have to use the dedicated vray shaders (and there are many dozens of them...without any good documentation)...
C4d has a command line render client
https://www.maxon.net/en/buy/license-options/command-line-render-client/Not sure it's the ideal solution for just 2 machines.
They also have a multi-seat license, but their site doesn't mention how much it costs...
I wrote to maxon support about those 2 options (about costs and to see if any of those options are relevant to me)
I'm beginning to see that for best workflow (on any renderer) will be to own c4d that has team render. This way I won't need to use dedicated vray shaders and will be able to work with corona DR when implemented...
Btw, looking at your c4d roadmap, I would implement DR before Node material editor. Especially now with the new cheap AMD 1950x threadtripper, and the upcoming intel 18 core chips - It makes the costs of a small home render farm (1-3 machines) much much cheaper...just my 2 cents of course :)
I also see in the road map that nothing has changed since the 28/8/2017....Hope it's just temporary because of your move to the new offices and the merge with chaos-group...
Kobi