MSCWolf,
First, if all you have is a 4'x8' space, I might suggest a change of scale to N instead of HO. Reason, HO mimimum radius on curves for some of your desired equipment, intermodals and six axle diesels, is 18", 24" preferred. That means a simple oval only for good running. With N scale, you could go down to 11" radius for the same equipment. That's just one thought.
B-)