Is it permissible for someone afflicted with intermittent anal leakage to adopt the Maliki madhhab regarding not changing the wipes or performing istinja' (ritual cleansing after defecation), and to suffice with performing wudu' (ablution) for each prayer, especially since doing otherwise causes him hardship?

It is permissible to act upon the opinion of the Malikis when there is a need and difficulty regarding the issue of continuous bleeding, for hardship begets ease. This is not considered seeking out dispensations. The Malikis obligate ablution in this situation, but they excuse the impurity of recurrent blood to alleviate difficulty.