How can we improve WHMCS?

Hi,

Userstory:
while WHMCS is focused on Webhosting, we also would like to use it not only for our webhosting but other customers as well. We offer IT Consulting in all kinds of ways. So for one customer we buy new hardware and setup a new IT environment at his location, for another customer we send an technician and fix his problems on-site or remote. Also we send our people to large scaled customers on a monthly basis where they work in projects for these customers.

So we would like to be able to manually write invoices when it is required in an ad-hoc way.

Let´s say we had a consultant at Company A for a month in a project. The consultant spent 19,08 mandays (consisting of 8,5 hours per day) in total at this customers facility. The invoice would have to look like:

Amount: 19,08
Unit: Mandays
Price: 1200 Euro (without tax)
Description: Project XYZ / Contract XYZ / IT Consulting for Company A, given by Mr. John Doe
Period: 01.05.23 - 31.05.23

Suggestion:

To achieve this, i want to suggest a feature in WHMCS (probably the "billable items" function could be slightly enhanced which should not be much of an effort) where the following things are possible:

1. Free-text define and save "Units" like "Mandays" or "Hours" or "Travel Expenses" or "Cellphone(s)", or any other good you regulary sell or have to put on an invoice
2. Free-text define and save "Billable items" that you oftenly (daily or monthly) use to have them available for a new invoice. Allow 3 or 4 Lines of description text and not only one
3. Ability to choose any of these pre-defined units and billable items when creating a new ad-hoc invoice and setting a fixed price for that item because you sell it more often
4. optional: Ability to create invoices without the need of saving/adding the customer (like a "guest invoice"). Sometimes you just write an invoice for a customer that you will never see again and also some customers dont want to have their data saved or being added to the system (GDPR/data retention etc.)

The process could look like this:

Create new invoice -> Add new billable item -> Select Unit -> Select amount -> the rest is being calculated by WHMCS.
E.g.: Create new invoice (for customer xyz): -> Add pre-saved billable item (with 3 lines of descriptive text and fixed price of e.g. 1200 Euros)

IT-Consulting for Barnslig and Sons Ltd.
Consultant: Mr. John Doe / on-site (London)
Contract Number: 124356hsd25655
Period: 01.05.23 - 31.05.23

-> Add the "unit" and amount =

+ Manday(s)
+ 19,08

I have added a screenshot of our current billing system that allows these features but cannot be used for compliance reasons in the future. Maybe this helps for a better understanding.