plumepack doesn’t appear to natively support .wmv.
Premiere does have a built in feature called SMART Rendering for lossless rendering. It also renders 4x faster this way because there’s no re-compression.
Unfortunately, it doesn’t appear either solution supports .wmv
You’ll have to choose between lossless and lossy encoding.
Some codecs at higher settings can give near perfect quality and visually lossless, like prores, dnx, cineform at high or ultra high settings without going full uncompressed into extremely large file sizes.
There may be a trim program that can natively cut wmv. perhaps ffmpeg can?