Can you do it (run the device off 120 volts using a converter)
YES. but.. (Oh that BUT)...
THe macerator can draw 20 amps or more (Stalled rotor is blows a 20 amp fuse nicely) So you need a heavy converter. I would suggest a Progressive Dynamics 9145 or whatever the smallest 9100 is. or equal. A plug in stand along single stage converter.
Or you can do what I did.
I ran 10 ga from the fuse block (30 amp fuse) in the RV (NOTE the fuse block is very handily located for this job) to a "jack" on the outside and I sue an extension cord for the remote tank. also 10ga, matching connectors.