As suggested, I have copied my posts regarding the Bachmann undergound Ernie as a suitable power unit.
This is a picture of the light, a nice bright useful little unit.
A little extra weight will probably help, but for less than £6.99 it is great value for bashing.
This is one I butchered.
Just hack them off, there is enough strength in the baseplate side pieces left to hold in place the pick-up/wheel holder pieces.
It took longer to type this message than it did to cut them off with a piercing saw.
Hopefully these pictures will explain.
Tried one out tonight, would not run
Fiddled with the wheels and got it to run, but only single axle drive, strange becasue each axle has a gear wheel, so i took it apart and found this:
Note the middle cog at a strange angle, no wonder it ran on one axle only!
Easy fix, took about a minute to put right and runs fine now.
Here you can see the pick-ups and where they collect power from the end of the axles, so should be easy to keep clean.
This is the power unit detached from everything.
These are the component parts.
This is the circuit board, the rectangular bit of board 3/4 of the way up is the plug into the 8 pin DCC socket, this just pops out to make way for your decoder plug. I will try a decoder at the weekend.