Here is the one key issue I see with your plan. Once your dad has 10 mortgages, there is no way you'll be able to get any more. Your income simply doesn't support it (1k/mo) and he will not be able to co-sign for you because he is already on 10 mortgages.
However, just because you can't get more than 10 conventional loans, doesn't mean that you can't get more than 10 loans. You'll just need to go with commercial loans at local banks to continue adding homes.
What I do see thats going to make it very easy for you though is the fact that your dad has good income, good credit and great reserves.
If you buy the houses right, you might be able to buy 4 or 5 houses a year with a combination of conventional and commercial loans.
I believe that the conventional loan req is that they won't count rental income unless you've been a landlord for 2 years. Thats going to hit his DTI pretty quick depending on the price point you'll be at.
But a local bank is going to be a lot more lenient and they will likely count that rental income so his DTI will qualify with them. And with 300k in the bank, they're going to be willing to lend up some money in an area like phoenix where the prices seem to be stabilizing (just from what I've read mine you) and/or even going up.
If you can take down 4 properties by putting down 20 to 25% and paying rehab costs out of pocket and your target properties are in the 100k range that you're getting all in for 80k, you'll likely be out of pocket about 30k per house or 120k total after buying the first four.
But after that, you should be able to start refinancing those homes at 75% LTV to get some of that money back out. Rinse and repeat.
As long as you can keep 100k cash in the bank, you're going to have
no problem getting more loans and continuing to add properties.
The only issue I see is that I don't think you'll be able to qualify for any loans so you're probably going to max out at 10 conventional loans and have to go with commercial loans for any more than that.
But, heck, I say go ahead and get to 10 as fast as you can. Real estate - if you buy right - is going to provide the best return you're going to find for any investment on the planet.
I think I mentioned this to a buddy the other day.
But try buying 100k in stock but only offering to pay 80k. And then tell them you want that 100k in stock that you're getting for 80k with only 20k down. Then try getting that stock to return a dividend of 6k per year (30% cash on cash return). And then see if you can write off a loss (i.e. depreciation) on that stock even though it goes up in value to 103k.
When you can find a stock like that, let me know. And I'd put everything I have into that stock. Until that time, I'm staying ALL In with real estate.