If you can track down Wheels and Tracks issue 23, there is an excelent article by David Fletcher with original pics and engineering drawings.
There is a great pic of one of the prototypes bogged down in mud nearly to the top of the hull, with a bunch of soldiers with shovels preparing to dig it out (188 tonnes burried at least 5 feet into the ground), I imagine it might have taken a while..........
I can just imagine the response the Maus's commander must have got when he had to get help to dig it out - "You bogged WHAT!! WHERE??!!! "
The Germans painted a fairly dodgy Hammer and Sicle on it and took some photos, apparently so they could use them for propaganda purposes, saying it was some huge Russian vehicle they had captured.