So you have an "unrestricted" category in both spectral rod and max camp tier category, which implements using different glitches to max out the run as fast as possible, but there is a little twist in the rules which makes those runs a lot more difficult. If you want to solo speedrun unrestricted category you have to make a solo world, in which (as of 1.10) you cant send letters (to yourself specifically). What if unrestricted category had a special rule that you have to set the max player count to 1, so noone can join, and you can set the world type to anything? That would make maxing unrestricted a lot more enjoyable and less rng-based.

if youre talking about using the dupe letter glitch theres a different method thats slower that can be used to dupe