Whether towing with a dolly, towing with a trailer, or even towing a trailer where the weight is is indeed key.
I've towed for years with everything from a Caprice SW to an F350 sd LWB and can tell you without a doubt where the weight sits is key.
I have seen a school bus being rocked by a camper/travel trailer improperly loaded with the team's sports gear, experienced the death wobble while towing my race car because I had to put it on the trailer backwards and with the weight very far back due to race damage, and even had a W126 sip n pass car rock my F250 because I loaded it backwards and tried getting over 70km/h among others. Slowing GENTLY controls it and speed is a factor.
If you MUST tow with the weight at the back just take it easy.
If you are towing and you get the death shake try moving weight forward of the trailer axles or moving weight to the tow rig. If you cannot simply go slow.

I won't comment on the capacities and weights of this situation but it had absolutely nothing to do with the steering or how the vehicle was secured to the dolly.

I am mostly happy it ended well for the individuals involved.

__________________
I don't know the same things that you don't know.

Shayne

85 W126 SD OM617.951
87 409D 650S OM617.913
93 E34 Touring M50B25TU
02 E46 Sport M54B30TU