A declaration is not necessary for an altitude claim. However, an Official Observer is necessary. The Official Observer must witness that the logger is in your aircraft prior to launch and download and save your flight log from that logger. 

Paperwork & Forms will be made available at the camp.

One thing that is often forgotten is that a 'notch' or other indication of being 'off tow' is necessary.  This indication must be obvious from your trace. Please ask if you have any doubts about an appropriate 'notch.'