I think the general attitude here is "bad idea" from the veterans & "give me a good reason that makes it a bad idea" from the people open minded enough to try something new. Bottom line...
Bottom line is, it ain't a new idea. Very few ideas that people come up with haven't already been tried by someone else. Without looking, I'd guess there are 10 or 15 threads on the use of camping trailers here on EO over the years.
The reasons it's a bad idea are, too many shippers and receivers won't let you on the property with a camping trailer. You can get to a shipper for an ASAP-right-now pickup, for example, and they won't let you in, and now you've got to go find a safe place to drop the trailer, which can take hours. You've blown the pickup and lost a customer. If your leased on with a carrier, they've lost a customer and you're likely to lose your lease. Another reason it's a bad idea is that people will steal your trailer in a heartbeat, especially when they see you drop it and quickly leave without securing it. Precious time can be wasted obtaining permission to leave an unattended camping trailer, even for a short period. Then that short time can turn into hours and hours if you are unexpectedly delayed for hours at the pickup or delivery. Then there's the sheer joy of having to go and unhook a trailer, go make a pickup or delivery, then come back and hook the trailer up, all in the pouring rain or in the middle of a blizzard.
All of the above has already happened to people who thought they had just the kewlest idea ever. All of the above are also reasons which have been given in past threads to the same kewlest idea ever.