This sounds like you are putting your fears ahead of everything, including your partner's comfort. For your partner, this sounds like a terrible sexual encounter.
From a technical view, the condom will help. The soap might or might now - probably not substantially, if at all.
STDs don't go through clothing, so wearing underwear will help with the skin to skin part.
Dilating her vagina - the vagina is elastic, so to speak. It stretches. You don't need to do this. Use some lube and it will ease the way as much as a sex toy would. Lube also helps prevent condom breakage.
Your partners deserve respect from you. If you proposed this idea to me, I'd just leave. I'm not some walking, talking herpes infection. If you can't handle a very small risk, you shouldn't have sex with someone who has herpes.
It's okay if you can't handle the risk, but don't leave your partners feeling terrible because you can't.
It's hard to say if the soap will help, but the condom should help.