Is your feature request related to a problem? Please describe.
There is no Rubber Sign or Rubber Boat, making this mod's Rubber wood type not match vanilla wood types in what can be made with it.

Describe the solution you'd like
Add a Rubber Sign and Rubber Boat.

Is using Terraform still an option for Tech Reborn to have rubber signs and boats?

Doesn't look like me much has changed regarding the boat in Vanilla. Could be doable though

Nope, still not viable

Won't fix.

Vanilla doesn't provide easy way to extend neither BoatEntity nor bunch of Sign related classes compare to slabs, stairs, etc.
We have two options - almost full rewrite of vanilla classes or wait if there will be changes in extensibility in 1.17 and later.

I've choose second option due to a lot of efforts to be spend on cosmetic stuff.

Feel free to re-open when MC 1.17 will be released.

Interesting. Given that TerraformersMC was able to tie into the boat and sign classes with their Terraform library https://github.com/TerraformersMC/Terraform, I had thought that this was simpler than it is. Would it be possible to ask for their permission to use that library to make this work?

Terraform replicated vanilla stuff.

For example boat:

Ah, gotcha. Well, you could still ask to use it to make your job easier.