Proposals -- in this case, proposals to yourselves for the Group Project-- can be helpfully constructed as failure standards. Failure standards are a real-world use of the falsification concept from experimental science, where a theory becomes ranked as scientific only when it is capable of being falsified in a replicable experiment.
So, for your assignment proposals, you would list (in either essay or point form) the full set of criteria by which your project can be gauged to have failed. for example "Our project will have failed if:"
- it does not meet the criteria detailed in assignment post
- the project does not advance an academic thesis.
- the project does not have [some measurable degree of] quality
- the project does not identifiably incorporate relevent scholarship
- the project fails to relate to some number of the primary course texts
- the project fails to represent and demonstrate advanced understanding of the central ideas of the course
- &c, &c.
An effective proposal describes (nb. look up the etymology of this word in the OED) three components of a project:
One to two pages is a reasonable length for a proposal of this type, four pages at most.