Physically I can`t see why not it`s just the expense of getting long enough cables made, but you will have problems with signal degradation and interference.
I think you really need to talk to an experienced engineer, perhaps at your local TV or radio station?
The problem is how to get those "long enough cables" , If is no commercial cables out there is because it doesn't work out so maybe I've to use another type of cables , shielded or whatever... coxial perhaps? but how do I send the signal through a coxial cable. There is a coxial - VGA converters?
Yes, it is possibble to place a CPU from the Monitor maximum of 40 Meter distance. But there is a chance of losing graphics resolution. to avoid the lose of resolution VGA converter can be put in the both end.