I’ve had some problems with FEDEX and UPS parcels containing cellphones and related parts but never had a problem with USPS. Custom brokers here advised me not to use FEDEX or UPS or DHL because they are more well known by customs to be for business use and thus dutiable. The post office customs house in Taipei is much easier to deal with than the import customs houses at the airport terminal.
I would separate your items into 3 different shipments mailed a few days apart as smaller parcels would get thru easier than big ones.