Professional credible clear face shot.They much rather know about you, than anything else.With direct mail marketing .. heck with investing, you really need to stop considering sellers being this unknown entity in this equation.

But I've left the old carpet down while major wall work is being done, and there's an unknown amount of floor damage from radiator leaks etc that needs to be repaired.

Otherwise, it would be legal to be here unknown (who knows, maybe it is). 

To summarize with your numbers, you'll need $15K (down payment), $15K (repairs), $5ishK (bridge loan costs), $2ishK (refinance costs, if you don't roll them in to the loan), $2ishK (holding costs before revenue generating), and to be on the safe side I would throw in another $5-10K for the unknowns.  

Don't worry about every minute detail, you cannot be paralyzed by the fear of the unknown or all the possibilities of every situation that may happen. 

Also, I do not partner with others here and rarely partner anymore at all, again, don't need to.I saw where have not posted for about a year, so I don't think you can claim to be an old hand here on BP, but that's not important, as I pointed out the posts above are unknown regardless how long they have been lurking.I'm certainly not a techie, anyone here will tell you that, but simple tried and true old methods work every time.

Aloha,Maybe I am not understanding your post correctly...you have one Tenant in a duplex that has been "paying rent" to an unknown person and living there for over a year, and you have not received a dime?

One thing to consider when determining and deciding over rents is to weigh the benefits of long term tenants vs dealing with vacancy periods, upgrade cost if any, and dealing with the unknown from any new tenant.

There are too many unknowns to your question.

@Shane Boyd fear of the unknown and its alot of physical risky work.