If you go to a manufactures home dealer they often will have there own finance companies to help out. Do a google search for manufactured home dealers in the area you want to buy and you should find your answer on their page.... more
They will stay flat until the fed starts to increase the fed funds rate. In doing so, it will cause the carry trade effect to be squeezed and institutional investors will start to require a higher return on investment from MBS. I did a short video (a few months ago) that explains the carry trade and why/how it is effecting current mortgage rates.