What difficulties will be faced making modifications for the Falcon 9 FT rocket, so in this way to make smoother, better and easier landings of the first stage from a GTO mission?
For example increasing a little the rocket size in height or diameter so to have a little bit more fuel to burn up 5 more seconds longer or even less than 5 seconds, just to give a better chance for successful landings. Of course modifying in that way that the aerodynamic pressure will be still ok. Another option could be a better engine performance so how much should be increased the performance, the thrust for example since the specific impulse usually is difficult to increase. This could increase the weight of the engines but engines weight is to small compared to the entire fueled rocket weight. So increasing rocket engines thrust in that mass that the new performance gives the rocket 5 more seconds thrust ( 5 seconds is taken as reference just for example ) at the final burn before landing. Another option could be a 4 or 5 engine burn more shortly than 3 engine burn before the final burn with 1 engine at the center of octaweb. Maybe this would not be a good choice but just i am supposing as option that could be better in the same way that SpaceX changed for GTO mission from a single engine burn to a 3 engine burn technique. What difficulties will be for this options which i took as examples or even for other options that could be as possible variants. These modifications or tests will have a cost and probably increase a little bit the cost of Falcon 9 FT but the SpaceX prices are still the lowest in the market and will be lower if a first stage lands successfully much more often and easier going toward perfection and 100% successful landings.
All this description was as an idea or possible suggestions.
So in a simple question what would be the challenges for SpaceX team to make some kind of modifications which will give more seconds to burn up longer the engines and landing easier and safer the first stage?