Another Moto Tote endorsement here, mine has worked great for 10+ years. Without an enclosed trailer, I needed my small pickup bed for carrying gear and it was too full with the bike in it. I found the original model locally for a very reasonable price of $250. It is very well built but also HEAVY to install. After a few years, I broke it down completely to media blast and re-powder coat it. I also replaced the hitch mounting bolt for peace of mind for a few bucks. With the bike loaded it does block the license plate and most of my rear signal lights. The carrier light kits seemed overpriced to me, so I added one of the adhesive LED light strips designed for a pickup truck bed to it. The super bright LED reverse lights on the strip are great for unloading the bike or gear in the dark. Some adhesive anti slip strips to the ramp and main carrier channel make loading much easier with debris stuck to sticky track tires.
I forgot to mention that part. I added some of the magnetic tail light/turn signals you can pick up in any of the box stores. After loading the bike I just stick them on.
Prolly not relevant for your Grom, but remember that the carrier itself is beefy (I believe my mototote is like 70 pounds), so make sure to take that into account when calc'ing the tongue weight.