All you can do is invite them. It is their decision to come or not. If their reason for not traveling is a financial one, maybe offer to put them up. If it is something eels like medical, or they just don't travel, there isn't much you can do. If they are special to you, have a photo book made up of your big day and send it to them as a gift. You can't change everything for two people, but you can let them know you are sorry they won't be there.
I am getting married but the guests we are inviting are in 2 different states and less than 20 people. There are 2 in West Virginia and the rest in Ohio. How should I celebrate it with the 2 in West Virginia? They are not willing to travel!
Video tape the wedding with a live feed that they can access. Greet them a few times live on camera.
Give them an itinerary of events. Guesstimate of the time of cutting the cake, garter belt toss and first dance.
This may be a bit over the top but If you know they will be watching, send them a paid for take out meal ( pizza ! ) delivered to their door timed for when you are having your sit down meal.
Well RefreshMe has a much bigger heart then I do! This is your day. You said they are not willing to travel. I'd say it's their loss. Concentrate on YOU and your husband to be. It's YOUR special day.
Now if they couldn't come because of finances or job won't let them leave or a sick grandma or something then I would have more heart but in my opinion it's very selfish of those TWO people to expect you to accommodate them on your day. You have 18 more guests to worry about.