It all depends on the walls you are hitting.

That depends on a lot of personal factors such as your finances.

@Stephen Karathomas The values of mobile homes and what you can pay for them depend on the area(s) you're working in.

Even as a Foregin National you can still take out up to 75% Cash out depending on your citizenship. 

Patio door prices can depend on the Model of Patio door you are looking for, for a standard 60x80 in white it will cost $1900.00 colors can be added, and for a patio door 72x80 the cost will be $2100.00 Outswing for a 60x80 will cost $2600.00 installed, and for an outswing 72x80 it will cost $2700.00 installed outswing with Grills for a 60x80 costs $1860.00, and an outswing 72x80 will cost $2300.00 installed.You also add blinds to all sliding and outswing patio doors for an additional charge.

Second, success often depends on creativity, persistence, and a willingness to negotiate.

The seller will lose some rent, potentially incur costs to evict, possibly costs to clean out the units depending on your sales agreement.

For example college rentals generate some of the highest ROI of properties I come across in New Jersey but it depends on the school and location of property.

Seems doable, depending on a few factors will determine what the right product is for you.

It depends.