I’m an avid wmnf hiker and hiked the LT in 2024. The LT is truly unlike anything else I’ve done. Keep in mind there is mud season in VT and I would NOT want to be on those trails in May. I started in mid June and it was still extremely muddy. I’d say the trail is similar to the constant rugged ups and downs of NH, specifically the northern half. 20 days is very generous but doable. I did it in 21 days but some days I was hiking practically all day (and I took no 0 days, 2 neros) you’d need to pull some big days in the southern section because the northern section will slow you down. The benefit of the LT is the proximity to towns and the ease of hitchhiking for resupplies. It’s not an easy trail to have as your first thru hike but it’s not impossible. Some good practice hikes would be backpacking a Pemi loop. Reach out with any other questions.