@Nick Wiswell your kind of getting beat up on your newbie post, and I hope it does not turn you off to the group. There is a bunch of great people with lots of knowledge and ideas. Let me go back to your original questions:
1) Since this is obviously a lot more work than stock market investing (and a lot less liquid, too), I'm looking for 15-20% cash-on-cash return, given a 4.25% interest rate. The 50% rule suggests it should be possible, but I'm not sure if that takes into account property management fees.
Am I crazy?
It can be done. Crazy is all dependent upon the point of view of a person. I think that we all agree on this point, so I don't think that asking this question really is going to evoke a solid answer.
2) Should I be contacting a real estate agent at this point? If I partner with someone here, do I even need one?
If you don't have "boots on the ground" you definitely need to find an agent that you trust. Finding a "partner" is much more difficult then you give credit. You might be able to shoot emails back and forth with somebody, but that does not necessarily mean they will partner with you, nor does it mean you should partner with them. At least with an agent, they have a legal obligation to look out for your best interest. I am not saying that anybody here would rip you off, but if I was going to partner with a newbie, I would go through a pretty strict vetting process. And I would expect the same from the other person. If they did not... I would be careful.
3) Will I need to take more than one plane trip? I expect to need at least one, but the fewer the better, since I've got a regular 9-5.
If it were me, I would take many, many trips out, especially if I was looking for a partner. Once I had a STRONG relationship with that person, I would cut back on my trips. I know that there are many people on this forum who invest out of state without ever seeing their property. However, I feel that these people have lots of experience and good people on the ground. Your success will depend highly on the team you create. The only people who have chimed in on this strategy are people who have been successful. I would imagine there are many more people who got burned or lost money because the people on the ground took advantage of them. "Buyer beware", but that is hard if you don't see the product.
4) Any ideas better than Milwaukee?
I think you have already made your decision on Milwaukee, so I am not sure why you are asking this question. Many people with LOTS of experience are trying to say that investing near SJ can be done and profitably, but you are answering these folks like they are totally insane to even suggest that option. Go to Milwaukee, cut your deal and blog about your experience here on BP. I have only been in the game for 2 years, so I consider myself a newbie. I personally would be really interested in a blow by blow experience of a newbie expand out of state.
Good hunting to you!
-Arlen