That's how I would build a limp range from SB and my preliminar estimate of EV, any thoughts are appreciated.

In a nutshell, I think it's a -0,575BB strategy if BB follows a very basic strategy of raising 100% of his range (assuming raise to 3BB)

Tree construction goes as follows:
- SB raising 0-20% of his range.
- SB limp 21-50%
- - SB limp/calling 21-30%
- - SB limp/folding 31-50% ( for a loss of 0,5BB)

Isolating only the limping strategy, I assumed only two very basic scenarios when limp/call:
- 15% will hit something and the pot would go x/call (0.5 pot bet) x/x x/x and SB wins the SD (6 BB profit)
- 85% will not hit anything and x/f for a total loss of 2.5BB

So the EV is:
67% * -0.5BB (2/3 of the limping range is folding)
33% * 85% * -2.5BB
33% * 15% * +6BB
Total = -0,575

I know i made a lot of strong assumptions on the BB atittude and didnt considered any draw, floating or x/r strategies but as I said is a simplification for a rough estimate of EV.
I run some simulations with different range values like 20-40% limp/calling range and all are negative. One needs to assume really the best case scenario to reach a +EV in this situation.

And I think what is more important is that even if you are able to reach a slighy +EV, the upsidr potential is SO limited that I don't think it's close to make sense.
Hope I did it right.

^To be honest this is the kind of reason why people suck at poker.

Reasoning in very theoretical terms is generally useless, and most - if not 100% - of your assumptions are bonkers anyway.

Well, as I mentioned, any thought is much appreciated.
Thank you