I have a shell for my truck. I have done a few transports and taken fosters to the vet, using my truck bed with the shell on it.

I prefer to have the dog in the cab with me, but the cab of my small truck is uncomfortable for large dogs (great danes for example), and it becomes a hazard when transporting more than one. Many times I used a large crate (48 inch long by 30 inch wide by 35 inch tall) to be able to make transports more manageable.

You can look at my webshot albums, of my Transports 2003.