Do you think a regularly-updated VM image would help promote pickup ?
I'm thinking something pre-configured (with the exception of the bitcoin wallet and payment address which will be created once the VM starts)
I don't think it's necessary to go this far. Some more details in the step-by-step instructions, so that they work without assuming the user's setup is 100% default would be enough.
For instance, the instructions on
http://p2pool.in/ might work for a user with a default setup (data folder for Bitcoin Core not modified) and who doesn't care about not knowing where the mined BTCs will arrive, but it's not enough for a user who moved around their data folder or wants to specify at the pool level the address where to receive BTCs. Also, it's not the case for me but maybe instructions to use a custom port (+/-IP) for Bitcoin RPC would be useful too.