Jorge;
Looks GOOD! I just love these StuG loaded-up with stuff- a really common scene in the historic pics and about as cool as things can get for a modeler- IMHO!
I DO have a couple of suggestions:
Remember that this is a lurching, jolting ride.... stuff will settle down into its lowest and most-compacted seating pretty fast.
So... a few suggestions: Those helmets probably want to get down into the stuff- crew would not leave them up where they might get lost, and a loose helmet would probably roll down into some crack or gap, I think. The empty bucket would probably have stuff in it - maybe it could have some rags and small things, or maybe some fire-wood, or some rope, or maybe one of those helmets, or maybe some canteens or.... ? That shovel.... I think it would look more "typical" blade-in. Whenever I pile tools into my truck, I generally tuck the blades in- the more so if I think someone might be climbing up onto the load...
And maybe crowd it up with various little bits?
The challenge in loading these vehicles up, to me, has been largely trying to come up with the small bits... lots of pics show loaded StuGs- with a real mix of things. The large stuff- barrels, gas-cans, buckets, crates,- are all pretty obvious. But my impression is that there was also a lot of smaller stuff and odds n ends tucked in. Additional road wheels, track-pins (a bucket cargo!), loose tools, things crew have collected, stuff unit infantry tossed on- bed-rolls, personal equipment, ammo cans and barrel-cases for MG-34/42, grenade boxes, mortar-round containers, souveniers. It's the odd junk which adds some special character. I've always found those pics showing a bicyle or a chair or someone's sewing machine to be specially interesting and reflective of the Germans carrying along both their spare parts and supplies and the bits and spoils of war.
GOOD start and it's going to look really really cool whatever more you do to it, whether or not you add or change!
Bob