Uninviting guests without burning bridges

My fiancé and I live in a different state than our friends and family. When we announced our small wedding, we offered to pay for accommodations for anyone that wanted to/was able to fly in for the wedding (basically, if they covered their own flights, we cover everything else). We also made it very clear that we understood if anyone couldn’t make it due to the travel, we just needed to know.

I gave a deadline on the RSVP’s so we would have enough time to book accommodations and catering. Well, that deadline has come and gone and many of the guests are still giving vague “I’m still looking at travel” answers when I check with them. We’re at the point where we have to have our final numbers to the caterer and accommodations we’ve booked for guests.

How would you politely tell those who aren’t giving a straight yes or no answer that time is up and you can’t accommodate them now? I’m especially struggling because one of these people is my lifelong best friend (very much wanted her here and don’t want to ruin our friendship but uninviting her), who I offered to also pay for her flight, but isn’t responding one way or the other still.