Filtering compressed air is 2 part, oil/particulates and moisture. Always filter the oil out first, then the moisture. The farther away you can mount the filters the better, as that will give the moisture/oil time to cool/condense to droplets and be much easier to remove than vapor. Run you compressor in short bursts to avoid getting high outlet temps that won't allow moisture to condense. Using a cooling water bath before/or submerge the desiccant filter in an ice water bath might help. Also paying attention to keeping the temp of the compressor coolant water very low might also help. Just some thoughts from someone very familiar with compressors/gases/filters.
Filtration temperature, among other factors, has an significant impact on the filtering process. Filter efficiency is also impacted by the oil concentration in the compressed air as well as the amount of free water. Don't over fill your compressor with oil, not even a little. Efficiency specs in the filter specifications always applies to a specific air temperature, usually 70°.
jmo