Hi Halo,
Just thought I'd give my advice as an FTM.
I prefer not to have my downstairs dealt with as things are at the moment, but that said, I am completely satisfied by my partner.
We use a 'tool' called a 'share' by lovehoney, a cheaper version of what's called a feeldoe, some guys aren't cool with penetration, fair enough, but for us it's perfect.
I can easily come with my girlfriend as can she, she can even give me hand jobs and ->-bleeped-<-s just like a bioguy
That said, I'd enjoy sex with my girlfriend with a strap on, as you see it just for your pleasure, for me 90% of enjoyment for sex is making sure my girlfriend is enjoying herself, pretty sure I could get off from that alone!
So yeh, I'd say things will naturally flow into what you both are comfortable with, but I'm sure you'll be able to more than satisfy him

If you guys are able to be open with each other it'll really help, and as long as you can assure him he's your man I'm sure he'll be able to say what he enjoys, and if not you'll soon be able to find out