man, i hear you on the ronin sc. that thing is a tank in the worst way possible. honestly, i tried to make the Zhiyun Crane M3S 3-Axis Gimbal work for my travel setup too, but unfortunately it was a bit of a letdown with anything bigger than a prime lens. i had issues with the motors vibrating once i started zooming my lens out, and honestly, it just felt a bit flimsy for a daily driver. its not as good as expected when youre actually out in the field trying to get quick shots in a place like japan. if you want to stay under that 400 buck limit and actually enjoy your trip, i would look at the DJI RS 3 Mini Lightweight Gimbal. i managed to snag mine on sale recently and it fits right into my Peak Design Everyday Sling 6L alongside the camera without being a total pain. it handles the weight of the a7c ii and that 20-70mm way better because the motors are actually meant for full-frame setups, not just beefy point-and-shoots. basically, the crane m3s is okay for tiny setups, but you are gonna regret it with that f4 zoom if you want smooth footage. sticking with the rs 3 mini will save you a headache and your wallet wont take a massive hit either. its kind of a bummer that the ultra-compact gimbals still struggle with basic full frame zooms tho... we just arent there yet.

tbh skip the zhiyun stuff for this specific kit. over the years ive found the DJI RS 3 Mini Lightweight Stabilizer is basically the sweet spot for the c series. it weighs almost nothing but the motors are surprisingly strong... handled my 20-70mm f4 like a champ. usually retails around 280-300 bucks too so youre well under budget. just make sure you balance it right and you wont have any issues in your sling.

honestly its so frustrating when specs lie. i tried a setup i thought was perfect but the motor vibration was just unbearable with a front-heavy zoom. unfortunately the roll axis kept sagging under load. i eventually had to move up to a model with higher voltage motors to get actual stability. how much weight are you adding with a cage or filters? the torque limits are way more finicky than the payload ratings claim.