You can put the bulb inside the tank so it'll be closer to your beardie's basking spot but it's probably safer to try to leave the bulb above the tank and raise the basking platform instead.
Beardies love to climb so that'll work out a little better for him/her.
I only used my Repti-Sun for a few weeks but I don't remember it getting very warm. It's probably still not a good idea for them to be able to touch it or possibly climb onto the fixture. Aside from the heat, there's also the risk that they'll get shocked :shock:
Hope that helps