You need to be able to do it with technique before you go. Unless things have changed your upper body will be smoked by the time you get to the obstacle.

Most of the height obstacles require upper body strength, so it makes sense to conserve as much of that strength as possible. I would practice using my feet/legs climbing until I reported.
If you are in shape and get past zero day, I think you will find that it's academically harder than it is physically.
That doesn't mean that Zero Day and the Forced March are fun.

You can do this...Practice Practice Practice..Take time between sessions to give your body time to respond...Eat protien every day..add "Boost" or other proteen shakes to your diet every day.. Atitude is what is important...If you tell yourself you will fail, then you will fail..be positive. Your a smart young man. Convince yourself that you can do this....you will be successful.. I was 157 pounds and a "geek" when I went to Ranger school at the age of 20.. but I told myself I could do it...My tough obstacle was the Pull-Up..could only do 5 - and I had to do 10. One day an instructor saw me drop off the bar and sneak to the next obsrtacle.. He caught up with me and asked me if I had done 10? I said no, he sent me back to the pullup bar.. I could then only do 4..he walked away and I fell off the bar and went to the next obstacle..he caught up to me again and asked me if I had done 10? I said "no" and he sent me back agian..so it went for the next 30 minutes..I was missing supper as all the others had already left the course. I was crying by then. He caught up to me again and told me that I should quit the Ranger Course and that he would BREAK ME this way. I was crying uncontrolably, but I told him that "he might win" , but "it would take him all night!" He looked at me and told me to go to supper. He never harassed me again...and I grew stronger each day--you just have to have ATTTUDE- that's what they want to see. Good Luck...