well standard is using the different options Darth has provided.
Otherwise if i understand your question correctly just change the script multiplier line in your user script
.EG.
campaign_unit_multiplier 1.0;
oh yes and dont change the unit sizes in your options, it should list as 'small', just check the unit size in custom setup
1.5x = 300 yari ashi
2.0x = 400 yari ashi
But i would excersise some caution as there would be a reason why there arent more options provided by Darth, i can only assume anything bigger than 2x and the BAI will run into issues
Darth has done his utmopst to sort pathfinding issues but there is still some vanilla bugs that havent been addressed yet.....