How about a home made Signal tester? Something like a coffee table about 4 feet long,2 feet wide, Maybe a foot or so high with a wire zig- zagged on the bottom with a wire lead and an alligator clip to clip on the earth ground. . Something really light that you could move around very easily and clip on to the wall outlet's earth ground. . Nothing fancy perhaps even made from a card board box.
Just place it over the engine instead of your hand.