Dealing with excess heat
Typical ovens with electronics use a back panel to place the electronic components on. Putting an additional panel above or to the side of this panel will provide the best location. Mark has a good point though test the temp experienced at the location you plan to put the project before you start to build. Each component you use should have a rating given by the manufacture of the max heat the component should be exposed to. You may also consider using an old pc fan to place in the enclosure to aid in keeping everything cool.