“It has to be built so that no Democrat can render it worthless.”
The bollards are heavy steel pipe, stronger than streetlight poles, filled with concrete and rebar. They will withstand the environment for many decades, with only surface rust.
They are very hard to breach, and relatively easy/quick/cheap to repair. They would be tough and expensive to demolish, if the Left ever went that far.
When thirty foot bollards are unguarded, few people would try to climb them, rather than find a way around them. They are scary high. Most people who fall from thirty feet, die from the fall - and those that live are badly hurt. It will happen, and word will get around - Mexican TV will broadcast the stories.
I'll bring the popcorn.