Part of the taking the clothes of is 'she does because she can"... is she Toilet trained? because I'd probably let her go the nap time (which I assume is now quiet time) without the pull up & see what happens
In terms of the bedtime, I'd give her lots of chances in the day to change her clothes (its a skill she is working on) & at night, pretty much let her be & once she is asleep go & get her dressed... she may even end up staying dry at night without a pull up, I know at that age my DS2 stayed dry because he refused to wear a pull up to bed & I refused to buy into a test of "who is the most stubborn" because really when we say our child is strong willed then generally we as the parent are too & that is where it comes from our battle of wills... if the battle ground isn't there then the problem is less.
The fact she won't sleep when she is exhausted may be because she's reached a point that the naptime/bedtime routine is no longer appropriate for her needs. I found there was a point where I had to change things around eg bath before dinner because it hyped up rather than calmed down, longer story time etc, sometimes the issues are more about a need for change in routine than anything else.
