243 is a great cartridge (although terrible barrel life), but I think you will be very glad to have your 7mm-08, the 7mm class offers probably one of the greatest ballistic coefficient bullets right now.
Not trying to tell you what to do. But if we take a look at PRS or ELR guys, you will not find a lead sled within miles of where they are, the only people I see using sleds these days are on the hunting network or guys who probably shoot 20rds a year with their “hunting rifle”. And I think there is a great reason for that. Yes the lead sled will give you an artificial rock solid position, but that’s about where the “pros” end for it. Like you said, you don’t consider yourself a great shot, that is even more reason NOT to use a sled. Yes there is a difference between practicing basic fundamentals of marksmanship and load development, but I do not think they are done separately. As for as SD, FPS, and ES. That is even more of a reason to not use a lead sled, if you are concerned with variations, why would you use a sled when you aren’t going to use when in the field, its best to practice how you will be shooting in real situations. Shooting without a sled offers you valuable information as well, it will instantly tell you what you are doing wrong or right.
If you cant get comfortable behind your rifle on the bench or prone with bipod and rear bag, than something is wrong. Either your eye relief needs adjustment, you need to add some sort of cheek riser or stock pad, or you need to adjust your fundamentals. When you fire a round with a sled, it also doesn’t allow you to see where your natural muzzle rise is. If you are prone and your reticle is constantly hopping up and to the left/right, maybe you need to have someone look at your positioning and line you up straight. If you are using a bipod and you bipod “hops”, you need to figure out how to load it correctly. Lastly a sled is a terrible tool because it takes away the recoil impulse and felt recoil onto the shooter. Especially with a lighter rifle, you want to practice with direct contact with the rifle and feel the recoil impulse. Over time, this can help reduce flinching and pulled shots.
If you take the time to check off your fundamentals and find a rear bag you like (wiebad, str8 laced, precision underground, bison tactical, Armageddon gear, TAB gear), you should be able to get into a rock solid position, practice your fundamentals, get great feedback on your rifle, and get accurate data for your load development. Like I said, if you can find a bigger rear bag dedicated for load development, it should take 99% of the shooter error out. Then you can practice with a smaller rear bag that is more field appropriate (I use a str8 laced bag in the field, it probably weighs like 4oz compared to my precision underground which weights like 2lbs).
Not sure what your budget is for a rangefinder. But Eurooptic has the Leica 2700R for 500 bucks. I don’t carry binos at the moment, but the glass for the leica is pretty sweet and I can spot goats easily at 800 yards with it, granted the FOV isn’t the greatest. I went with the 2800com because it will instantly laser and send the range to my kestrel (in my pack) with applied ballistics and spit out a holdover for wind and drop into the leica. If that is something you do not plan on using, the 2700R will serve you perfectly.
If you ever see a maroon beat up camry at kokohead, just look for an Asian guy with bright orange rimmed glasses and a shaved head and im always willing to chat more with you in person