Remote Desktop redirects the port, rather than the printer.
The host machine then must have available an appropriate printer driver for
the remote (client) printer.
LPT ports are redirected by default, so I think you are OK there. The next
hurdle is having the printer driver available at the host end.
Check the system event logs on the host machine around times of RD session
connection and look for error messages indicating a lack of driver. Install
the driver on the host.
You can do this remotely, getting the driver from the printer makers web
site. I typically install the most minimal possible across-the-network sort
of driver, set to print to LPT1.
Once the "printer" has been installed, you can highlight the printer in the
printers folder, and delete it. When prompted whether to also delete the
files involved, say NO.
You should then be able to print fine to the remote client printer, while
not having the printer cluttering up the printers folder at the host end.
If the host is a server, proceed with extreme caution, using only signed
drivers certified for the server OS by the printer manufacturer.