Passenger car trailers around how much loads? Increase empty mass to save costs?

Hello, I have to let a trailer load up to 1350 kg. No problem from the technical point of view, all parts are suitable up to min. 1350 kg total weight. Now my question: What can be mounted “useless” on a trailer, so that one is with the payload at a maximum of 1000 kg? The trailer has an empty mass of 310 kg in the vehicle certificate. Meanwhile, however, some parts have been installed (automatic support wheel, supports, lashing booms, wheel shock absorbers for 100 km/h etc.). The total weight is currently 1000 kg. What really counts for the unladen mass? Everything that is firmly connected, or bolted or welded? Is it possible that it makes sense to have it only charged up to 1200 kg zGG due to the vehicle control? Cost yes per 200 kg zGG 7.46 Euro per year… Is it possible that another total weight makes sense to choose the towing vehicle? Mostly the trailer is pulled by a Golf 4 (empty mass 1376 kg, towing load 1400 kg, 1500 kg to 8). % incline); what are common weights of golf class vehicles? I hope this is not too confusing 😉 Greeting Pinarella