When I had Lasik my doctor suggested taking Neptune Krill Oil pills to help with the dry eye. Might be worth looking into.
I wonder if you could do the BB1500 over 36 hours and try to stay in the daylight. That might be easier and safer than trying the SS1000 in 24. I left at 0630 and finished my 1000 miles around 2230, so I spent about 2 hours in the dark. Got up late the next day and finished it up by 1600. So if you shifted times a bit, you could probably stay in the daylight and do both.
If you want, I can post my spreadsheet with my times and locations to give you a feel for my pace.