Is it really possible for a team of just two or three sales staff to manage over a hundred customers simultaneously?

Having limited staff is not inherently a problem; the question is whether you have a system to eliminate repetitive work. If every quotation requires manual entry, every purchase order needs manual file assembly, and customers asking about conditions means searching through emails for old versions, then two or three people cannot scale. However, if the system automatically populates a customer's quotation terms and payment methods, automatically notifies sales after a customer inquires on the page, and maintains version records for easy comparison, sales only need to review and confirm rather than recreate everything from scratch. With this approach, a small team can serve multilingual, multi-currency, multi-country buyers. The key is setting up master data and trading conditions once, then letting the system multiply each person's productivity.