I did a shoot at a golf course near a Class D with 0' max AGL and got approval up to 150', which is what I requested. The course is hilly and had many trees. Not sure 50' would have been sufficient to get a good view.
I had to submit many requests to cover multiple days due to the need for decent weather for the shoot. My requests for single days were approved quickly, usually within a week.
I submitted a request for a full week. Got questions via email about it. It seems like multi-day requests come mostly from construction companies wanting to document progress. Despite answering all their (FAA) questions, the desired dates passed before approval/denial. If you try a multiday request you will need to give a lot more time for approval.
One handy feature is to re-submit a request that was previously approved (as I recall there is a box you click on to do this). Those seemed to get almost immediate approval. Only disappointing thing is you can only do this once per approved request. You can't piggy back a request by re-submitting a the approval of a re-submitted request.
Good luck...