Yes, I also use a rubber ducky for bench testing.

If you want to fabricate something, you could take a chassis BNC connector (male) and solder 10 carbon resistors of 500 Ohm (or 470 Ohm), 0.5 Watt in parallel from the center conductor to the ground. This makes for a 50 Ohm (47 Ohm), 5Watt load.
Don't use a 50 Ohm power resistor as those are mostly wire wound, which would be an inductance.

If you are sure that you are not going to (accidentally) switch to transmit mode, you can do without an antenna, but with a rubber duck easily accessible, I would not take that risk.
If you accidentally transmit you might damage your RF power amplifier.

3U