Hi VanellusVanellus,
Thank you for reaching out to Microsoft Community.
When using a USB-C charger to charge the Surface, we should keep in mind the charging requirement of the Surface. You mentioned that the USB-C charger you'd want to use is a 45W charger, the Surface Book 2 uses two different charger for its configuration. 44W for the Surface book 2 13" (without NVIDIA GPU) and the 102W for the Surface Book 2 13" (with NVIDIA GPU), Performance Base or the 15" configuration. Please check which Surface Book 2 do you have. See this page for more details in Surface power supplies and charging requirement: How to charge Surface.
For the bundled charger, we respect your opinion on the weight of the power supply unit of the Surface. You may submit a feedback on this through our Feedback Hub. See this page for details: Send feedback to Microsoft through the Feedback Hub.
If this answer your question, we highly encourage you to inform our Community by clicking on Yes or marking my post as an answer. This will help other members who may have the same issue as you. Otherwise, don't hesitate to update us so we can further assist you.
Kind Regards,
Marrion Y.