I would personally be careful with any pulling (as Janet also said). However the idea of having uke move forward to lose their balance a bit more certainly works. I would just suggest you have them do it to themselves (or you guide them into it) rather than pull them.
Two things I play with when receiving a shomenuchi strike are:
1. Move in and block the strike before it gains power. From their you can move either to the side or back (without pulling) and change uke's direction of strength/power since uke should be feeling their balance go into their back foot.
2. Move in and really pretend to block so that uke starts to think about hitting your blocking hands and then back off so their strike goes past where they thought they were going to hit. Then block them their. Here it's easy to pivot or move back since uke is leaning forward about to fall on his face :-)