No p2pool use PPLNS.
Payouts are not based on shares since prior block but shares in a set number of prior shares. All shares which are paid out are worth the same. It can't be hopped*.
Simple version is hoppers exploit the fact that each block reward is split among a VARIABLE number of shares. So when number of shares is small the reward is worth more on a per share basis. When the number of shares is large the reward is worth less on a per share basis. This dynamic only exists in prop pools.
*Technically there is a very small and slight window when difficulty changes but it is mostly an academic risk. Some pools like Bitminter use shift based PPLNS to reduce even that small vulnerability.