Seems like 500 is about right. How much could you stuff in the Olds? That is why I brought that point up. How about a Dodge 3500 dually with a camper top? 20K lbs???? Which one can travel under a TFR without notice?
Since you own an airplane, you know as well as anyone that anything with wings is easily sensationalized, and makes a great whipping boy for the media.
Not to mention, most cars now days are actually faster than the 150 (105kts ias).
Well, if an IslamoBadGuy didn't mind flying over gross, 500# might work. If he's an FAA-standard-sized IslamoBadGuy, there's about 450# of useful load left.