Precision-Controlled RC Car Design

Hi there, I am looking to builder a fun custom project. I have a technical concept for an RC truck that needs to actively balance carrying a heavy payload while maintaining a decent top speed. I am interested in testing mechanisms like a custom multi-speed gearbox or an active suspension adjustment system to handle the changing weight. The Deal: I have a budget to fully cover the parts, plus your fees. I will buy all the components you need directly from AliExpress, Banggood, or Amazon and ship them straight to your address. You get to keep the physical truck and all the hardware when the project is done! What I need from you: The digital design files or code used. A few videos demonstrating the truck driving fast while carrying the payload weight. If you are a scratch-builder or custom fabricator interested in taking this on, please reply to this thread or send me a Private Message (PM) with a picture or video link of a past build you've done. Thanks! 1 - Physical size? The smaller it has to be the more difficult it is to cram 10 pounds into a 5 pound sack. As a truck to be 1/10 scale is the most suitable one. Can be 1/12 if possible to achieve. 2 - How heavy is a heavy payload? One pound on a small scale truck is heavy, fifty pounds on a larger truck may be light. The payload on the boot ( preferred ) or as trailer to be 5kg roughly. 3 - What's a decent top speed? 60mph at 1/24 scale is about 3,5 feet per second. At 1/4 scale that's 22 feet per second. Not exceeding 20-25 km/h for the scale mentioned above. Stability is key. 4 - Any particular configuration? 4X2, 4X4, 6X4, 6X6, ETC.? That is negotiable despite the thought that 6x4 could be the optimum choice taking into account the payload.