I wouldn't personally do it, however if I really felt the need, I'd just stick a tuning box on there and remove before return - added bonus is that you can then sell it on and recoup some of the initial cost.
That said, even without looking and finding a remap, if they wanted to, they can deep dive on the ecu to find different values (don't know what they are) and find stuff to flag it as it's had a tuning box on, but if they don't find any physical evidence, they're not likely to look.