B2B and wholesale stores need different checkouts for different customers: invoice payment only for approved trade accounts, freight delivery only above a weight, no cash on delivery for export orders. This plugin handles both halves with one rule screen:
AovUp Rate & Gateway Rules Pro adds fees and discounts per shipping or payment method (fixed or a percentage), a table rate shipping method (weight, subtotal or item bands), postcode, coupon, weekday, time of day and customer history conditions, messages at checkout that explain a hidden method, and rule import and export.