Two suggestions
One as noted the Hula Skirt will not do much to protect the towed. IN FACT it may have just the opposite effect and throw rocks up.
Now Think like either a Furnace/fireplace installer or a motorcycilist.
If you are installing say a Pot Bellied Stove in a house. the pipe inside the hose is single wall but once it hits the ceiling there is a Triple wall pipe. A pipe inside a larger pipe inside a still larger pipe with the occasional spacer to insure they do not touch each other.. Air flow between the pipes is sufficent to keep 'er cool
Motorcycles have a "Guard" chrome plated and perforated around the exposed side of the exhaust pipe.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times