Not sure if you could cut this down that far without changing the end product, unless you can find some Vienna malt extract.
If you can steep grains, you can do a partial mash, trust me! Give it a shot and you'll see! The only difference is that you measure your water better and mind the temperature closer. If you wanted to make this one a bit easier, you could convert the pale malt to more LME and that would cut the grain bill down to 4 lbs, making it a little easier to manage thought you'd be stretching the Vienna's enzymatic power a tad bit. If you add the extra LME at the start of the boil, and save the rest for the end as the recipe calls for, it'll help keep your hop utilization the same.
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