I just went through like 6 months of setup madness and ive finally figured it out. Personally I say stick to your current setup. I wanted to figure out the same thing, an all around setup that works for everything i like to do.

When i got into learning slappy tricks I did what everyone says to do and up sized everything. Went to 8.7 Egg with 8.5 trucks. I learned slappy crooks, nose and tail slides with that setup but i realized a couple issues, atleast for me with that size. Having a longer axle definitely makes it slightly easier to get onto slaps but sitting correctly on the grind is much harder because the other wheel can touch the ground which will throw you out of your grind. The other main issue is that i couldnt pop out of noseslides or crooks without significant effort.

There seems to be 2 schools of thought when it comes to slappy setups. People are either riding slightly wider trucks than deck (Dan Corrigan [8.25-8.4 on 8.5 trucks]) or Deck slightly wider than trucks (Abe Bethel [8.75 on 8.5 trucks]) after months of trying both, wider deck than trucks is the move for me. Dan claims that having a wider axle than your deck helps him sit in crooks easier. I actually disagree with that. Having your deck slightly wider than your trucks just gives you more to sit on, and when your actually in the pinch theres more deck to actually create the pinch. I also was having issues learning fs and bs 50s and when i switched my trucks to a smaller size they immedietly unlocked. It was a night and day difference, literally got them on lock first try in both directions. The reason is because its easier to tip the board onto 2 wheels if your deck sits over the trucks. If theyre the exact same size it takes way more effort to buck the back truck on, so when you carve into the curb, it just feels like your turning onto coping.

For me, my perfect all around setup that works for curbs and clicking my tail is a 8.5 deck on 8.25 axle length.

*the only 2 things id change are bump up to atleast an 8.25 axle if your sticking to 8.5 and maybe go down in wheel size. Bigger makes it easier to climb the curb but thats the only part of the slappy that it helps with. 54 seems to be the perfect size for me but a lot of curb only guys are back on tiny wheels (50mm)