Hi. I worked on a specialist stroke unit for many years. You are welcome to message me and arrange to chat.
If you don't fancy doing that, then as you have passed an assessment, you have been deemed fit to drive by those who give you a legal entitlement to do so...... but, if you don't feel safe to tow - then don't.
I'm guessing the assessment didn't include having your van on the back, and spacial awareness for all that extra length is not something that would necessarily come back to you straight away; in fact when we first learn to tow, it was usually a real worry for most of us until we get used to it all, so it should come as no surprise that it's worrying you now.
Get used to driving a standard length vehicle again.
Take your time doing this, maybe many months.
Do not feel pressured to tow by anyone.
If it doesn't feel 100% safe, don't do it.
Our brain is extremely complex - when it has suffered an injury it will learn/ re learn/ find difficulty in learning different things at different rates.
One thing the brain is consistently brilliant at, is protecting us from danger. If it's telling you that you shouldn't yet be towing, you should listen to it.