GVWR for the 16' Bambi is 3,500lbs. which is under the 4Runner's 5,000lbs. weight limit. The tongue weight with LP, not including any water or cargo is 350lbs. Unloaded trailer weight same spec is 2,900lbs. meaning that if the weight was balanced correctly, a loaded to GVWR trailer would have a tongue weight of approximately 425lbs. which is 75lbs. under the 500lbs. rating of the 4Runner.
That 425lbs. comes off of the 4Runner's "payload" capacity of about 1,500lbs. Rough numbers, you'll be left with 1,000lbs. to load into the 4Runner including passengers, mods, and anything additional.
The math for your 4Runner is up to you to figure out, but those are the general parameters. Quick Google search shows that the 19' Bambi will be well over the 500lbs. tongue weight rating loaded, so I wouldn't consider that trailer.