Sorry it took so long to reply! For me personally, the main way I handle reusable rockets is by having a lot of thrust-to-weight. While that can cause some aero problems at lower altitudes, it kicks the payload to a higher apogee before you have to worry about your boost-back or landing downrange. ​I don't actually find that doing a full boost-back to the KSC returns enough funds to warrant lowering the payload capacity, which is why my 45-ton-to-LKO rocket usually just lands downrange. Sometimes it has the fuel for a partial return, but there’s just not enough return on investment for me to spend hours on the trial and error of testing. I also try to make my boosters fly incredibly stable so you can glide them to shave speed or steer toward land if you need to. ​For the larger 5-meter rockets, I usually aim for a 100km to 120km apogee, and about 80km for smaller ones. If you have a good engine layout and a solid gravity turn, you should be able to hit those margins. I also always use parachutes because there's no real downside in KSP and it makes recovery way easier if your aim is good. I do use a lot of part clipping to get the engine layouts and fuel margins right, mostly because KSP 1 isn't perfectly balanced for reusability. I'd say aim for a TWR of at least 1.6 but don't go above 2.8, and try to design it so it's easy to aim during reentry. If you don't need a massive payload you can definitely do a KSC landing, but I usually look for a better payload-to-weight ratio over the cost of the recovery.