Investment Properties

I have a customer that wants to refinace his two rental properties with and interest rate lower than 10%   Now here is the catch…  ONe property is valued at $21000 and the other at $26,000.  His credit score is 521 but he has no lates within the last 5 years, He just has a “lot” of credit.  This is a full doc and he makes $10,000 a month. He currently has in total 4 properties, 1 primary and 3 rentals.  He also is thinking of purchasing another investment property but he only wants to put no more than 10% down.  This property is valued at $40,000.  If anyone has the solutions please Help Me