Can I rewrite 德里克.帕腓特有一个极端得空前绝后的假设 using 的 or 地 instead of 得？
For 极端得空前绝后的假设, 空前绝后 is describing 极端, to express the degree of 极端. And 极端 is describing 假设. So 极端得空前绝后的假设 could be parsed as 极端（得空前绝后）的假设, means (unprecedentedly) extreme hypothesis.

And when describing the degree of verb/adj, 得 should be used.

Note that in the 2nd sentence, if you change 得 to 的, the syntax is valid but the meaning changes; it becomes 极端的，空前绝后的假设, both 极端 and 空前绝后 describe 假设, means extreme and unprecedented hypothesis.

For the 3rd sentence, I'll say that using 地 is wrong syntax here.

Here're some references about the differences among 的, 地, 得:
「的、地、得」的用法有何区别？
“的、地、得”的用法