How was your boyfriend diagnosed with genital herpes? HSV1 or HSV2? Have you been tested to know your own herpes status?
The virus is known to shed through the entire anogenital area, so covering only the two spots is not very productive.
Is he on suppressive therapy? If so, the chances of transmission are already pretty low. If you're willing to give him oral sex without a condom, why not talk to him about it? He's probably aware of the lower transmission risk associated with suppressive therapy. Besides, catching oral hsv2 is much less likely than catching genital hsv2.
Take a few minutes to read this handbook about herpes - it has all the info on transmission risk while on suppressive therapy: http://www.westoverheights.com/genital_herpes/handbook.html
Keep asking questions!