Do you think applicants would be willing to share the kitchen with 3 others?

My last Detroit Metro eviction took around 4-6 weeks between slow application process, bailiff scheduling conflicts, etc. 

For example, I mention that every adult must pay a $30 application fee, pass my credit/criminal background, make a combined income of 3x the rent, and whether or not the property accepts pets.

If you do not feel good about it, deny the application based on the son's statement that he is going to live there, or for other disqualification reasons.

There is financial benefit in keeping quality tenants, reducing tenant turn over, and having multiple tenant applications to choose the best tenant.  

Michael says that it becomes part of the 3-tier application of the payments received by my former tenants.

Quote from @Andy Ramos: It is not illegal, but it is unreasonable.The leasing fee covers all the work associated with moving the old tenant out, supervising the turnover, marketing, screening applicants, getting them under contract, moving them in, etc.

I think at that price point the temptation is too great to accept the first applicant.  

I require all new tenants to use it, but I have a few that use other methods due to them being tenants when I acquired the properties.Background and credit checks are easy to send to an applicant - they pay 55.00 and I get the reports quickly. 

I know you're asking about 75% LTV and non-owner occupying so perhaps this is not that applicable, but considering a househack might not be out of the question.