RFP responses are sales documents, for sure, but they’re not brochures.
So don’t go for nice-to-look-at over easy-to-read project sheets and equipment cut-sheets.
Use font that’s big enough to be legible in your narrative. You need pictures, but pictures alone won’t carry your message.
Use left-justified text, not fully justified, which is just too hard to read in quantity, and too weird in tables.
Set production values that reflect the one-time use of the proposal, not the again-and-again use typical of brochures.
Filter information in headers and footers for the communication purpose. Don’t bother including the contact information, for example, that is typical in brochures and project/equipment cut-sheets. For that matter, you can likely dispense with your corporate logo. No single proposal page has to stand on its own, as a brochure often does.
And, oh yeah, don’t go all high-level, generic marketingese. This is not a come-on, it’s the sales pitch itself. So for equipment, give details about the make, model, capacity, features, and benefits; for projects, give details about what you did, how you did it, and what the benefit to the client was.