Take a look at Tenant Cloud (www.tenantcloud.com) and see how that program works for you. It is FREE for less than 75 units. Great reporting tools, online payments, online invoicing to tenants, there is an App for it as well where tenants can pay, submit work order requests, and you can even track inventory for the equipment you own in each of the trailers.
You can also set up recurring bills for water, etc.
There is also Cozi (www.cozi.co), but not as versatile as TenantCloud.
I manage 4 parks using this application and have not had an issue....even made it easier for our accounting professional with the exported reports