It probably won't have much effect, if any. These rules were originally promulgated to give daytime-only stations a chance at eeking out a morning and evening drive-time audience in the winter.  The calculations take into account what is known as the "diurnal factor".  This takes into account the fact that skywave propagation doesn't peak until 2 hours after sunset,  and starts to recede at two hours before sunrise. Section 73.99 goes into great detail about the conditions which must be satisfied, but the bottom line is that Canadian stations must continue to be protected .
The diurnal factor calculation which applies in this case is detailed in the Canada/US AM Agreement as well as Section 73.190)  It is a rather arcane procedure, and involves calculating the diurnal factor for the specific frequency using four variables. The factor is 1.0 at 2 hours after sunset or 2 hours before sunrise. At sunset itself, as an example, the factor may be 0.2, which means that you can radiate 5 times the field strength (or 25 x the power) without interfering. But if your protection is such that you can only radiate 10 watts towards a Class A station, multiplying by 5 doesn't buy you much. There are stations with nighttime operating powers as ridiculous as 7 watts. But being on the air means that you can continue to simulcast your FM translator.