Ikea Kallax/Expedit help!

[Twinklefuck]

I've got a Kallax 2x4 unit coming for ds' room and as its a small room it'd go either tall-ways and fixed to the wall or long ways across the floor but can't fix it to the wall if longways as itd be in front of the radiator.

I'm worried in general (haven't seen it in rl) that if its tall ways it could still topple forwards (will be using those special bolt things that grip from behind the wall but will the fixing into the unit be strong?) so if we have it long ways across the floor we couldn't fix it to the wall at all, more dangerous or more steady as weight more evenly distributed that way?

Ds is mostly always supervised when playing anyway (unless I nip to the loo) and I realise how neurotic I sound but what would you do?

We had one in DSS's room for a while which was upright. He's 12 so no worry of him swinging on it though. It was sturdy enough to stand upright without it being a concern for me. There is also one full of books on the landing upright.

There is another(a bit obsessed!) in the younger DC's playroom which is on it's side and is absolutely never going to fall over. They're pretty sturdy either way.

I have a 2x4 long ways and they're fairly sturdy - don't think there's any chance of it falling over - it'd need someone to properly push/pull it. Plus, long ways it becomes a handy extra surface for putting things on.

Thank you! My preference was long ways to have his bigger toys on but with no way to fix it to the wall it was driving me insane with worry. He's not even a climber when it comes to furniture what has parenthood done to me.