I use Esaki silk. it is very thin and can be had in a number of colors. It is available from free flight suppliers such as FAI Supplies, Aerodyne, MicroX, Peck Polymers, etc. It is somewhat expensive compared to Thai silks, which I have no experience with.
First make sure that all surfaces which will touch the silk are well doped and shiny. On the El Diablo, I would cover the top and bottom of the wings with separate pieces. Make sure you have the grain of the silk running spanwise. Cut out a piece giving you an inch or so all around. Lay it down on the wing and spray it soaking wet with water. Carefully arrange it, keeping the grain lines straight and no wrinkles. It is not hard to do, but requires attention and patience. Go over the places you want it to stick with thinner (I actually like very thin dope.) Trim the edges with a razor blade. Now do the same with the top of the wing. Keep all the silk wet until finished. When finished, hang the wing vertically so that both sides will dry evenly.
On the fuselage, I would do very much the same. Silk goes round curves very well. I would cover the stab, elevator, and rudder with either silk or similar color tissue.
Once the silk is dry, brush it with a mixture of tautening butyrate; 30%dope, 70% thinner. I brush about three bays and turn it over and brush three bays on the other side. There will be run through, but it won't show with dope this thin. After about four coats, the silk should be mostly sealed.
Now cut out your numbers out of tissue. I recommend Spectra black. Stick the numbers down with thinner. Then switch to non tautening butyrate and go with a thicker mix until it is shiny to suit you.