Adding extra weight is ok if done carefully.
Always check tongue weight if adding propane tanks or extra batteries to the hitch. Never exceed 400 lbs and reduce front loading inside the trailer to compensate for the extra weight on the a frame. Use the highway scales to verify the load on the trailer axle and also use a portable to check the tongue weight on level ground.
Our setup is a second 20 lb tank and 2 type 24 agm batteries with a total of 170 amp hour capacity. The second propane tank is used mostly for outdoor cooking capacity. We never use the factory installed external propane outlet as it is on the sewer/slideout side of our winnie drop 1780 and are considering removing it as it is getting corroded and I certainly do not trust it to not leak if connected to a long hose even though it is on the low pressure side of the gas after the regulator.
We find the biggest use of propane is either heating if off grid, or cooking if on grid. On grid we use a low watt quartz heater instead of the furnace.
The furnace is the biggest battery draw by far.
We never use the 12 volt function of the fridge as the fridge will drain the batteries in less than 10 hours. The propane function of the fridge, while off grid, is not huge. Even though it does use a fair amount of propane it is not bad if you carry an extra tank as we do.
Our tanks are not on a dual regulator as like I said the spare tank is mostly used for outdoor cooking and backup if we run out on trailer tank.
On average we can get 2 weeks camping off grid in cool weather by using a generator and 40 lbs of propane. But we do not keep the hot water on at night and only heat it up when needed off grid. If on grid we just use the electric functions on both the hot water and fridge. On grid 40 lbs of propane lasts a full season.
The down side of using two batteries is that two type 24 agms weight in at 90 lbs and the extra propane tank adds appx 30 lbs to the tongue weight.
Our tongue weight is up just over 400 lbs which makes the usage of a weight distribution hitch a good idea.
Adding the extra weight of another propane tank and battery is ok provided on does not overload the front of the trailer and then teeter totter up over 500 lbs of weight on the hitch.
The heavier Winnie Drops were a knock off clone of the RPod Trailer from forest river and were designed to be towed with an SUV. They are undersprung on the torsion axles and are prone to axle failure because of it especially if on off roads at all. The failure of the rubber suspension caused us to replace our axle this thread explains quite well
how the failure occurs as one owner actually took one that failed appart and found out how the axle degraded.
Fortunately your lighter winnie drop 170 should not be as prone to this issue but the 1780 model certainly was famous for having torsion axles fail.
Our fix when the lippert axle degraded and cambered inward at the top was to go to a sprung axle and not worry about having the rubber wear out on the low spec lippert torsion axle.
