Welcome rhenke!
That is a nice little camper you have.
We have what we call "brochure" weights. These are the weights Sunline listed in the 1978 brochure when it was being sold.
In our files section you can find this. On the top of the forum are "Tabs" which are hot links to places of neat info.
When logged in, click the "Files" tab, then look under "Brochures" search out 1978 travel trailers and download a copy of the 78 brochure.
On page 2 it says this on a 78 12 1/2 MC (mini compact):
Axle Weight (empty): 1,050# This was the weight when it was made that model at Sunline without any added options. There is no battery or LP gas in the tank.
GAWR- (total under-carriage wt.cap.(lbs.): 2,120# This is the max. weight the axle can support
Hitch Weight (empty): 100#. This was the tongue weight (dry) when the camper was offered at Sunline, again no battery, no LP gas in the tank and no added options.
Even a spare tire is an option.
The only true way to know what the weight is, to weigh it, like you have. Note: Using CAT scales or other truck scales has a tolerance on the read out. Many times it can be 50# +/- from a the real weight. When measuring 80,000# semi trucks, +/- 50# is noise.
And finding 2 different scales to be exact at a truck stop exact with each other, odds are low they will ever be exact but will be close.
The CAT scale should be a certified weight within the calibration tolerance. You can ask them what the tolerance is and apply that to the reading.
The margin for error is less the heavier the camper. If you want to find how close a scale is on your little camper, take a axle reading with just the camper on the scale. Then not moving anything, you stand on the scale with the axle and take a second reading. You know how much you weigh with shoes and clothes on from a home bath scale so you can see on the weight ticket how close it came to adding your weight to the camper and then estimate up or down depending on how far off your weight was. Re-weighs at most truck stops is at a reduced price. Sometimes only $1.00 in some places I have found. You pay the full price the first time.
Hope this helps
John