Hi there. Im commenting on ideas for your larger dragons as the little guy needs gentle handling - less than 5 mins a time really.
It might just be me but from the picture I would also question if he is 5 months... looks much younger in the photo with the other two.
Just like cats and dogs, some will tolerate being dressed up and some will have none of it. I wouldn't personally try dressing up a baby beardie.
Other activities you can try are:
1. Feeding livefood outside the viv. I sometimes use a 4m long shallow storage tub with tocks and things so they can hunt.
2. Set up a little assault course with bits of treats along the way.
3. Snuggles before lights out. If your dragon is energetic throughout the day, they are ususally quite calm just before lights out.
4. If its warm and sunny, you can get outdoor pens.
I hope you have lots of fun together.