Yes, long not good, short better, but I sure get a lot of emails telling me the opposite. In general, unless you use a pumped or crank pressurized system, you should keep the tank close to the engine.

However, if you select distant location, you can resolve most of the fuel delivery problem with a header tank. This "trick" is used in some pattern setups where having the fuel tank on CG is ideal. It is also used on many helis to prevent air in the lines during 3D, etc. Just get a small tank, say 1-2oz, and place it up by the firewall. It is plumbed to be between the primary tank and engine. You fill thru this tank back to the primary. Likewise, the engine draws thru this tank, with the primary behind. The idea is that the header tank will always stay full as long as the primary hasn't run dry, and the lines from this tank to engine are short. System should pressurize properly. This will slightly shift your CG forward, depending upon the size of the header tank, because the header tank will always be full of fuel (think of it as dead weight.) So if that is a concern, use a small tank and compensate accordingly. Cheers.