In theory you should be able to get the fourth loan. There are some “depends on” of course. The biggest challenge you are going to run into though is finding a loan agent that would be willing to invest the time to get your loan through. Your case will take some serious work, understanding of the business and in depth product knowledge. I think it is very telling that your question has had 53 views and no answers.. that kind of proves the point. If you are looking for that fourth loan and the loan amount is under $625K, you have at least 25% down payment and FICO scores over 720, guidelines grant you the opportunity to get that fourth loan on your own. You would have to be able to qualify on debt to income and reserves and so forth but that is normal stuff. Best of luck in your endeavors.
Theoretically, you should be able to get a 4th loan. Fannie Mae guidelines state that the cap is 10 mortgages. Some lenders have reduced that to 4 during the recent recession.
But here is the fly in the ointment, if you file joint tax returns, then the lender is going to take your total debt to income ratio into consideration. This is going to include all of your husband’s debt as well.