to your "dry" hitch weight add the weight of any battery(s) you have on the tongue, the weight of propane in the tank. Those two along could add 150lbs to the tongue weight and that is BEFORE you've put anything into the trailer.
Next, I'd advice to NOT try to carry ANY electric bike on the back of the micro mini. 1) you may move way to much weight off the tongue, bad (2) the bumper is not rated to handle that weight, 3) check around, there are almost NO bike racks capable of handling the weight of Ebikes that a mfg says are acceptable for use on the back of a travel trailer. A few for Ebikes on MH or 5th wheel, but very very few rated for use on a TT.
Next, tongue weight subtracts from the cargo and passenger weight. You have 900lbs, split it however you want between passengers, cargo and tongue weight but the total must be 900lbs or less. so if you have 500lbs of cargo that only leaves you 400lbs of tongue weight
