With the ride in August, I think there's time. I vote for go for it. Besides, it's a fully supported ride. If you get too tired, catch a ride. There's no harm in trying and you're not going to get stranded anywhere. You just have to give yourself permission to say "I've had enough" and not feel bad about it.
Oh, oh. I think I may have just convinced myself to do a hilly century in later in April.
Living life like there's no tomorrow.
http://gorgebikefitter.com/
2007 Look Dura Ace
2010 Custom Tonic cross with discs, SRAM
2012 Moots YBB 2 x 10 Shimano XTR
2014 Soma B-Side SS