I don't understand your method for setting the WDH (ie, XX amount difference in sag). Do you mean that you are trying to get the front and rear to drop ("sag") and equal amount, compared to when the trailer is disconnected?
Typical setting instructions:
-Measure height of front and rear wheel wells, before attaching trailer.
-Attach trailer and engage WDH. If trailer is not level, make necessary adjustments.
-Check front wheel well height. When properly set, it will be back to the original height when trailer was disconnected.
From your description, it sounds like you may have it set such that the front is lower than original. Unless you have a 3/4-ton truck or better, this will likely have your front axle overloaded! And if you have it set so tight that the rear wheel well is higher than stock, you REALLY have a safety issue!
Large trucks can go for equal-compression, letting the front drop lower than stock, because they have additional capacity in the front axle for think like snowplows, etc. I don't think your VW can handle such additional loading. For most of us, getting the front back to stock is the most you should go.
thebrakeman ('70), DW ('71), DD ('99), DD ('01), DD ('05)
2004 Surveyor SV261T (UltraLite Bunkhouse Hybrid)
2006 Mercury Mountaineer V8 AWD Premier
Equal-i-zer WDH (10k), Prodigy Brake Controller