Personal experience with a “small “, open car hauler for the Vette owned with three others back around 69...and current experience with daughters Uhaul open hauler
These were 7,000 lb GVWR open car hauler trailers. How much would an enclosed car hauler be?
An open hauler for most cars would be around 18’ long for the bed...maybe less if the car is a subcompact/2-seater/etc
Open car haulers in that range should be around 1,500 to 2,000 lb range. The OP’s father has a enclosed hauler. So it should weigh more...maybe 2,500 to 3,000 lbs
Small car should be in the +3,000 range...maybe a subcompact bit less. My Vette was listed at 3,000,but with the L88 we stuffed into it, it weighed several hundred lbs more
A full sized sedan might be 4,000 or more lbs
Then spare parts, tools, tire/wheels, misc stuff might be another few hundred lbs more...or they travel without any of these
So a #4 might be fine...or...not...we don’t know what the heck the OP’s father has in regards to an enclosed car hauler...
My small 2 seater weighs around 2,100 lbs with me in it...nephews small 2 seater weighs around 3,400 lb with him in it...same OEM, same model line...just about 40 years apart
”small” is subjective...as is “small” in regards to an enclosed car hauler...