Need a few more pegs?
Say you need an extra 5 pegs on the 41 peg yellow loom. You'll be using pegs 1-5 twice, once for each end.
Cast on to pegs 1-41, then cast on to pegs 1-5 again. Turn around and wrap pegs 5-1 and 41-35. Knit off pegs 5-1, and pegs 41-35, bringing the middle loop over the top loop for pegs 5-1. Move the top loops on pegs 5-1 to a stitch holder. Finish the rest of the row, pegs 34-1.
For the next rows, wrap and knit off pegs 1-41 as normal. Put the 5 loops on the stitch holder onto pegs 1-5. Wrap pegs 1-5, and knit off the middle loop over the top loop. Now go back, wrapping pegs 5-1 and 41 - 35 and knitting them off (for pegs 5-1, knit the middle loop over the top loop). Put the top loops on pegs 5-1 back onto the stitch holder.
You're making pegs 1-5 do double duty, and moving the loops off the pegs to knit one side edge of the piece, then putting the loops back on the pegs to knit the other side edge of the piece. It's a bit cumbersome, but it does work!