Shane, you can mount the large Peco/Hornby motors underneath without the big hole , Peco motor instructions show you how or even on top using PL12. With this, a building can be fitted over the top of the motor similar to the Hornby Unit R8015 http://www.hornby.com/search.html?q=r8015
Have not tried the new Hornby surface mounted motor but I am happy with the Peco unit.
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