Oh yes, you can use memory banking, but why on earth do so.
There are now dozens of '51 derivatives that support linear addressing to several megabytes. I know of the Philips Mx series and the Philips P89C669. Both those support 8Mbytes of linear addressing for data and code. Other manufactureres have such offerings as well. The only sad thing about this is that if you are using Keil you must fork out a bunch of money because they charge extra for the version that support this. If you are using Raisonance, the support is included in the package.

Erik