By "utilizes multiple lights with multiple render target" do you mean to say that it was a deferred renderer?
Light Pre-Pass (deferred lighting) doesn't require MRT and neither does forward shading. There is technically no limit to the number of lights either is capable of supporting. If you want to port your engine more or less as it is currently, you could maybe consider targeting OpenGL ES 3.0 instead. It's still pretty new, but there are already phones and tablets that support it, and ES 3.0 has MRT.