[janoskiss (Steve H)]

It usually does end up looking ridiculous if you push the power high enough and your focusser needs to be up to the job of coping with all that torque from the long barlow+EP barrel (looks like yours is a good one). One thing you may have issues with is focusser travel. Long barlows are more flexible for this sort of setup.

How well blackened the insides of your extension tubes are will matter for contrast. They should be matte black with no shiny bits. Installing a baffle or two may also be a good idea.