How much should a tow cost for bobtail?

It's a free market. I can charge whatever I want. Customers can decide to buy my service's or not. Based on their response.... I will respond accordingly if I want to survive and prosper.

 

I was an after hours tow guy for a bit last year. For a bobtail, in town, after hours it would have been $200/hr min 2 hours. So $400 for that 2 mile tow...but ya you can negotiate with them on it.
Generally, we charged 200-450+ per hour, plus miles(.90/mi) and tolls ($25 per) round trip from the terminal. I want to say my average bill was around $1500-1800 for a tractor trailer that usually took around 4 hours start to finish. Some recoveries got real expensive real fast, and I had zero hesitation inflating figures if you put me in a bad spot because of your stupidity.
Pro tip: 2am Saturday night in the middle of winter is not a good time to test how far you can drive your rig until it runs out of fuel on the shoulder of a surprisingly busy at that time highway.