Bitlocker encryption with remotely accessible password?

Question

Encryption

We use Bitlocker in the office on laptops of sales staff.
A USB disk (or SD) is used for decryption.
The question is how to make the decryption ability not depend on the USB-disk (or SD) but on some remote server? I do not want to move to VDI purely because of this. Because the channel is often unstable - employees work both in the office and in the "fields", there is also a 2G connection.