What else would you do though? Hire mining inspectors that regularily check mining operations around the globe whether they run hardware according to regulation?

Seriously tho, at the end of the day the most straightforward solution would be to simply get in touch with major mining pool operators. Given an attractive enough sponsorship deal you'd surely find operators willing to add your tagline to whatever blocks they mine. Whether this advertising money wouldn't be better spent elsewhere is a different question. Depending on ones intent this would digress from the original idea of incentivising people to use specific mining hardware though, leaving only the advertising aspect.