I don't see how a short consultation on the matter would exceed 3-4 digits. It's maybe an hour from a specialist to see what is needed. Saving your bacon later on is worth some cost.

Worst case, you might also have existing recommendations or fire code/regulations for battery energy storage systems in your area, and while those specifically may be overkill they give an idea of what is considered necessary. Maybe you could consult your local fire department, depending on how things work in your area.