Apologies if this seems so obvious, check the trailers tyre pressures are correct. I've seen quite a few trailers have a lil wobble due to incorrect tyre pressures.
I would extend the inboard straps to attach on the other side which would provide better triangulation.
No, just point out his school boy error - unless he meant "is this nearly finished strapping OK once I have finished it?"
A two bike shimmy on a trailer is funny to watch till you realise it's your own. Trailer neglect as often people just store it for ages then magically think the tyre pressures are okay, the wheels are secure, and the tyres haven't cracked yet, even though they have been outside for 4 winters. They are a means to an end and if maintained properly, weight loaded equally and secured properly, serve a great purpose giving many a rider a good day/trip out. Personally they scare me as it's like going to bed with a woman who sleeps with a knife under her pillow and you never being sure if both your heads will still be attached in the morning.
Both scare the bjesus Otta me... I've never used a bike trailer but have been to bed with a few pyscos..
Be concerned about scrotes following the trailer home then robbing the bikes, even vans who stick bike connected stickers on are not good, might look the part in the paddock but the bad boys know a van and number 46 or an arai sticker on the back means a wage. Better to hire this, the driver loves paid trackday watching....apparently
I've heard work vans are worse as they are easyish to find on a drive on a weekend afternoon/evening. Then they come back 11:00am Tuesday as know they'll be at work.