Temporarily installed cover plates with senders back in fuel tanks. Pondered bottom skin riveting and reviewed instructions. Clecoed bottom skin on left wing and checked to see if it was possible to install the pitot mast in the skin and over the spar flange with the first three rivet rows clecoed in place; it is possible. Tried reaching wires through bottom skin access opening and considered potential difficulties with connecting pitot heat wires. Removed skin; clecoed mast to spar flange and support bracket; slipped pitot/AOA into mast. Drilled small hole in support bracket and installed rubber grommet for routing pitot heat wire from conduit.
