I have tried to connect my Canon BJC50 portable printer to my Toshiba A105 4094 laptop which has no parallel ports. I bought a parallel to USB cable and it takes 10 minutes for a page to print.. if it ends up printing at all.
In talking to Canon they said I was out of luck.. that the parallel spoke a different 'language' than the USB.
Someone said to try going thru a router - but I didn't understand what they were saying.
This won't work because using a router would still need your adaptor, which you've identified as being a bit hit-and-miss.
A lot of laptops (and many branded computer systems) have dropped support for legacy connectors now, so you won't find serial ports, parallel ports or even PS/2 ports now on models like these. Heck, on the back of a Dell machine you get 5 USB Ports, a network port, video port and a sound hole. And nothing else.
If there is a workaround it needs to be something that I can still tote around with me without adding too much bulk or weight.
The only real workaround to this is to find another portable printer that works off USB, as the USB to Parallel adaptors aren't very good and usually cause more trouble than they are worth.