I assume the challenge is not the number of nights, but the fact the Travel Agent is making only making approx. 10% commission which doesn't justify the work involved for low value bookings.

I have used https://reisetopia.de/hotels/ many times for short stays - always receiving prompt and good service. However it is a German company with the website and communication in German - I'm not sure if they would accept a customer from US or communication in English.

I also considered this company, but have never used them: https://www.asmallworld.com/collection They are also European, based in Switzerland, but the website is available in English.