I can ( and will) give you my opinion about your H's sexual request, but I believe what's most important is how you feel about it. It's admirable that you want to save your marriage and that you are willing to listen and even expand your sexual boundaries, but at what cost? Being pressured to perform an activity that inwardly doesn't feel right for you will cause you to lose self respect.
When I started college I dated a guy for 3 yrs...it was a very intense love affair and I experienced many " firsts." One night we went out with another couple and found ourselves by a reservoir...by bf and the other 2 stripped and went skinny dipping..it was expected that I would join them but I just wasn't comfortable. It wasn't for me. Afterwards he was angry with me for not participating...and it was the beginning of the end of our relationship. I could ask 100 people whether I did " the right thing" but it doesn't matter...it was the right for me.
I know there is more at stake in marriage... but what is the marriage worth is you feel coerced to do something that feels wrong for you?
Personally, I can't see how intimacy is created by engaging in sexual activity with another person...I don't get it. But that's really not the point...it's more about how you feel.
What are some of the other issues you're struggling with?
