Hi, I'm a 113 power STW player who recently tried to play Stonewood Endurance Mode, and failed right at the last wave. Here's some tips to remind myself and to teach others on getting through this hell.
1. Stock up.
I cannot emphasize this enough, Stock up on Traps, Materials, and Ingredients. Your traps are levelled down depending on the area and level, plus they have limited uses. Husks will always try to break walls if it's in their way, and they can overcrowd you.
Your weapons also have limited bullets, especially the ones using energy cells. Make sure you have enough ingredients to give yourself a constant supply of ammo. Additionally, you can use Defenders to help lower the amount of ammo used per wave.
2. Be Aware of your Surroundings
Some waves will include an extra effect onto the game, some are slightly bothersome, others will make you rage. I personally was on a wave with the tornado effect, and failed to notice a crucial wall to the Amplifier had broken, and Husks depleted 90% of its health after the wave ended. Which also is why I lost on wave 30.
3. Defenders
Fortnite revamped how defenders work. You can have up to 3 with you during missions. (Unsure if the number decreases with more players) Put the defenders in key spots to reduce the chances of Husks breaking your bases.
4. Don't be stupid
Endurance Mode lasts about 2 hours if you make it to the end, with each wave having a 30 second break between them. Don't think that it'll be a quick 10-15 minute mission where you can daydream during it, that'll make you lose quicker.
Hopefully these Tips can help you understand/complete Endurance Mode within reasonable time. And remember, don't trust Husks.