Is there an invisible fence plugin kinda like in lifeboat

or is there a way to just remove the fence texture so it's just invisible

 

I'm not entirely sure how lifeboat does it, but you could use Invisible Bedrock, or you could create a block without adding the cooresponding tile correctly. The first one is easier.

 

Whats the block id for invisible bedrock

 

95. Now that I think about it, though, it may not be registered in pmmp.

 

its not i can place it but it disappears after a second and goes back into my inventory

 

You can use WorldProtect to do exactly this using borders :
https://poggit.pmmp.io/p/WorldProtect

 

And don't forget to checkout config.yml to turn on/off the features you want to use...

 

but is that like world edit or is it an actual block i would prefer a actual placeable block

 

It's got everything you need for that, take a look at the read.me and please let us know if you find any bugs.

 

If you really want invisible bedrock you could use a worldeditor.

 

There are no good up-to-date world editors I know of yet... WP also has unbreakable blocks. Borders are much easier though!

 

If this can help you...
Use Genisys pm phar and world edit to place inv. Bedrock and turn PMMP phar... I already done it and work.