First ""real"" trailrun

Hi all! I would love some advice (I'm 34F, btw.)

I'm still a beginner, been running for about 2 years, discovered trail running little over a year ago. I love offroad running and I've ran a couple of trail events, up to 24km. I do, however, live in the Netherlands, so not a lot of vertical meters. My most "impressive" runs were a 10k with 750 m elevation gain (1:59h, mostly stairs, pffft 😅 ), and a 21km with 600 m of elevation gain (2:47h). And a 24km with not a lot of vertical meters (I believe 150m or so), in about 3hrs. I must add that I wasn't looking to set great times in all of these, I just wanted to have fun! My best 10k road time is 57minutes, and I've done two HM's on the road in less than ideal circumstances both in about 2:20-2:25hrs.

Now I'm looking for some foreign trail runs that happen to be during my vacation periods (I'm in education, so not a lot to choose!). And I just got an e-mail I can pre-register for the Grand Ballot trail in the French Vosges mountains, which happens to be during my spring break in April 2026!

But I'm wondering, what would be the cut off times during an event like that? Can't find anything about it.

I would love to register for the 26km, to really have a challenge to work towards this winter. Or would I be better off registering for the 21km as I might underestimate the whole thing? (I'm really not, but I just hope I can make the times 😅). I've been on a couple of solo hikes and runs with trekking poles in Italy and Austria last summer and I know it's HARD and relatively (very) slow.

Any advice? Or maybe just a little nudge in the back to just DO IT?

Thanks a lot, guys!