How to 'cap' result of 'Trim with Regions'?

I think it’s time to upgrade my machine, but it would probably also be worth it to seek better ways to perform solid booleans.

Luckily a lot can be improved on:

My machine info:

Summary

Rhino 7 SR36 2023-12-12 (Rhino 7, 7.36.23346.16351, Git hash:master @ 11a364321297eb8cdb34405a3308d8911f58706d)
License type: Educational, build 2023-12-12
License details: Cloud Zoo

Windows 10 (10.0.19045 SR0.0) or greater (Physical RAM: 31Gb)

Computer platform: LAPTOP - Plugged in [60% battery remaining]

Non-hybrid graphics configuration.
Primary display and OpenGL: NVIDIA GeForce RTX 2060 (NVidia) Memory: 6GB, Driver date: 6-23-2023 (M-D-Y). OpenGL Ver: 4.6.0 NVIDIA 536.40
> Integrated accelerated graphics device with 4 adapter port(s)
- Laptop lid is possibly closed
- Windows Main Display attached to adapter port #1

OpenGL Settings
Safe mode: Off
Use accelerated hardware modes: On
Redraw scene when viewports are exposed: On
Graphics level being used: OpenGL 4.6 (primary GPU’s maximum)

Anti-alias mode: 4x
Mip Map Filtering: Linear
Anisotropic Filtering Mode: High

Vendor Name: NVIDIA Corporation
Render version: 4.6
Shading Language: 4.60 NVIDIA
Driver Date: 6-23-2023
Driver Version: 31.0.15.3640
Maximum Texture size: 32768 x 32768
Z-Buffer depth: 24 bits
Maximum Viewport size: 32768 x 32768
Total Video Memory: 6 GB