If you're going to abuse 'em, I'd almost suggest using Applecare+ for this exact purpose.
Either buy a second watch for the purpose of work and keep Applecare+ on it (I'm thinking it would set you back $140 a year at most, plus the cost of the watch), or just have 1 watch and replace annually under Applecare+ until you want to pay for an upgrade.
If you're going to abuse 'em, I'd almost suggest using Applecare+ for this exact purpose.
Either buy a second watch for the purpose of work and keep Applecare+ on it (I'm thinking it would set you back $140 a year at most, plus the cost of the watch), or just have 1 watch and replace annually under Applecare+ until you want to pay for an upgrade.