I don't know about using a 4P like that but I did see people carrying around the lunchpails from Compaq, Kaypro, and Osborne. Good thing the early 80s were a time when executives were expected to work out.
The 4P was rather late to the market and smaller form laptops started becoming commonplace soon after the 4P was announced. Another case of Tandy jumping on a market just as the market was ending.
IBM PC based lunchpails lasted a long time because they could include normal ISA cards and thus could do a lot of portable diagnostic tasks. I think I was still seeing Compaq Portable style cases used for network analysis through about 1995.