Wouldn’t it be an option achieving this mode in 5 minutes, by setting a switch in the radio for limiting Ail/Ele travel by a certain amount? Knowing the max set gps speed or max set angle in a given flight mode, it is simple to calculate the required rates.
For any decent gimbal, limiting attitude to -2…2deg would be just stupid, as it would make it impossible to hold position in wind for no reason.
There is no point in thinking angles (unless with a crappy gimbal with small movement).
With any normal radio, you can set up dual rate(s) so that by flipping a switch, a full roll/pitch/yaw would be a slow travel/yaw. (basically what @Anto6ka wrote) - make sure to reduce deadzone.
This already exists. It’s called “loiter” mode and you can set the maximum speed. You can also set maximum frame angle but you should be very careful because if the wind exceeds your frame angle you will be blown downwind.
Generally you should NOT use dual rates when using an autopilot system.
I use this mode frequently for close-in inspection work. I set to 2m/s and climb rate to 2m/s this keep things very sedate and controlled.