Yeah so what you'll do is run down to the local college, latch onto a mechanical, then hydraulic engineering class, then after you have that done, take a machine tools class and then build/market you own aftermarket valve kit.
They are not just simple devices like many think.
Kubota valves work on Kubota tractors and they just fit. Real easy to put on. They are expensive, but that M7040 isn't necessarily a cheap tractor either. I'm fairly sure that the investment you make now for OEM stuff is going to pay for itself come time to trade up, or sell. Aftermarket stuff is generally not even close in comparison. I do this stuff on a daily basis and it is VERY VERY rare for any aftermarket part to fit and work exactly like OEM; even sometimes the aftermarket company that is owned by the OEM. To my knowledge there is no aftermarket rear remote but I'm gonna watch this thread to see if maybe someone else knows if there is.