20 to 30 fixed mortgage for rental properties

I presently work with a local bank and have no problem getting loans. However all they will offer for rental properties is a 5 year fixed on a 10 or 15 year payment schedule. I haven't be able to received any fixed rate over 5 years nor any payment schedule more than 15 years. I listen to many of the I pod stating they are receiving a 30 year fixed rate. I presently have 32 properties so I have to many for the national banks. Any suggestion for this problem?