My impression is that you are far too worried about contracting this virus genitally. In general, you are extremely unlikely to contract it genitally since you already have it orally -- and since it's the exact same strain you have, it seems even MORE likely that your existing antibodies would protect you. It's also true that HSV-1 isn't passed genital to genital even if one partner is HSV-1 negative, since it sheds so infrequently from the genital tract.
That said, it is not totally impossible. I won't guarantee you anything. But to put it in perspective: even if you did contract it genitally...you already have it orally, so would it really make a difference, other than the mental stigma aspect?
If you want to be safe, your girlfriend could continue to take suppressive antivirals, but even that seems like overkill to me. Showering after every sex act is not only unnecessary, it isn't even effective in preventing transmission. Just avoid sex when she's having an overt outbreak.
Hi, hsv1 genitally is somewhat of a new discovery from oral and not many studies have been done but bottom line is that a person can get it in both ganglions. Taking meds does lower the risk but none the less the risk does exist.