Yes, it's perfectly possible to get a partner-sponsored work visa approved when for some of your time you haven't had a fixed base. (Here's one couple who started out that way - she got her work visa, then, the last we heard of them she was going for Residence.
http://www.enz.org/forum/showthread.php?t=39162) It sounds as though you've thought of the main kinds of evidence you can give. As for any partnership, try to find something which solidly shows the beginning of your time together, then add in as many different kinds of proof as you can to show you're still together as the time passes. Don't forget to date and give locations for your photographs. Do your finances show your connection? Think about if each of you has paid for things which are for the use of both of you. Do you have emails or other communications to and from family members that mention your partner?
Here are old forum threads about partnership cases, which might give your more food for thought.
https://www.google.co.uk/?gws_rd=cr,...te:www.enz.org
One more thought. Don't forget to keep on systematically collecting evidence of partnership while your application is being processed, and even after that. 1) It's very common for the CO to ask for more proof just before the visa is granted (to make sure they're not giving a visa to someone who has broken up from their sponsor in the meantime). 2) You will need all the time covered if you want to get Residence later on.