There are several options to get over 2Mb. You can use two Starbaord II units - they work fine together to get up to 4.5Mb.
Also most A500 side expansion unit work fine on an A1000 - They just need to be supported (stick a book under them).
In the past I had a GVP A500+ connected to an A1000 with 8Mbs of RAM and a 120Mb hard drive (fair sized back then) and it all worked great.
I have read about a newer expansion, that adds an IDE interface and 4Mb of RAM, but I don't know who is behind that (can anyone add that info?).