There is a lot of bad information in that post.
First, pretty much every 26" Lapua out there (which you say you have) will hit the 2750 node with a 300 Berger. That combo should easily take you to 2000+ yards supersonic. Your comment that you are "not sure Lapua is really for anything much longer" than 1000-1500 is showing your ignorance on this topic. Your 26" Lapua is MORE THAN ENOUGH gun to shoot 1000-1500. A puny Creedmoor in capable hands can make reliable hits at 1000-1500. Adding 6 more inches of barrel to your Lapua is not going make any difference in your ability to hit targets at 1000-1500.
Second, 50 BMG is a terrible choice for someone learning ELR for a whole host of reasons. Cost, recoil, muzzle blast, necessity for new reloading equipment, lower inherent precision than something like an XC or Cheytac. Just no. If you really wanted to graduate to the next performance tier (which it sounds like you do not have the skill or experience to do), something like a 33 or 37XC makes way more sense. And it would be compatible with your current action.
You still have not answered my question - what is it you think a 32" Lapua will do that a 26" Lapua will not? And what action do you have? Your inability to articulate this tells me that you aren't even close to having the skill level to maximize the performance of your current rifle. It's like someone with a Ferrari who has never driven it over 60MPH wanting to upgrade to a Bugatti because they think that is what is necessary to drive faster.
I shoot a 30" Lapua Improved and I am pretty much maxing out the performance of the Lapua case: 30" barrel, max capacity 40 degree chamber, long throat for 300 Bergers at 3.9+ OAL, single shot action, RL33 powder. It's about as extreme of a setup as you can get with the Lapua case short of the stepped throat Terminator design. The difference between my rifle and your 26" standard Lapua is about 200-250 fps with a 300 Berger. The extra velocity of even the most extreme, long barrel Lapua Improved setup will make almost no difference in your ability to reliably hit targets at 1000-1500.
Not trying to rain on your parade or be disrespectful, but you aren't asking the right questions.