Why dont you take some time away from wedding "stuff"? At least a week. There is no need to stress yourself or be stressed around your test taking probably stressed out too FI. Relax. I can assure you that an at home wedding is MUCH more work and stress than a DW.
It does appear that you really want alot of people to go since your are funding so much! If logistics are a problem, I would suggest having a AHR so that the grandparents and family and friends who dont make it, can.
Since you are funding your inlaws trip, would you mind just booking it at your location? It seems much easier and well... it's essentially a free trip for them.
I know you really want to please everyone but its time to step away from the ceremony wedding stuff and focus on what this is really about - You and Your husband. Make sure you two are taken care of first. I hate to see someone stressed out about 1 day of their life. Sometimes I get in this mode and I just have to walk away from it all.