Take a contrasting piece of yarn about 12 inches.I was putting 12 stitches aside,so, this was more then enough.Knit your stitches with the scrap yarn.Now thumb stitches are on the right needle.
Now slide them back on the left needle.
With your regular yarn knit right over your scrap yarn
and continue with your pattern like nothing happened.
When your mitten is done ,this is what your thumb area will look like on the outside.
This is how it appears on the inside.
From the inside,take out your contrasting yarn 1 stitch at a time.
You will be getting (for me)12 stitches at the top and 12 stitches at the bottom of the thumb.No need to fumble with picking up stitches they will all be there ready for you to knit your thumb.
Next time the finished project. Give this a try and if you have any questions feel free to give me a holler........................said the hobbit