Those references are not very useful. The dangers of over-promising when making proposals are considerable. Sometimes consultants get caught up in their own expert visioning and offer more than is required to get the job done. It would be more pleasant for all concerned if a value-adding service were performed as the opportunity presents itself. Their participation lessens the chance of misunderstandings and surprises.
Clients love fact-based, supported presentations.
The proposal serves as your collateral. It's worth the time it takes to check spelling and write as tightly as possible. You want them to see the quality they would get if they hire you. If in doubt, slow down. Anticipate questions that might be asked and practice your answers, to keep them short and to the point.