foolproof scenario to change site domain name without moving the site

Hi,
Here is the scenario:
I build web sites for customers. Mostly they have an exisitng web site somewhere (www.companydomain.com), so what I do is, I build the web site, on the final server, but with a temporary domain name (companydomain.mydomain.com). In wordpress, I activate the necessary plugins, hand the site to the customer who then fills the new site using the temporary URL, adds their own images, slideshows and whatnot.
When everything is greenlighted, by me on the technical/hosting side and by the client (or their multimedia and textwriting guys), I need to have a foolproof way to change the old URL to the new one.

I know that I have to modify the home and siteURL fields in the database, as well as the multimadia links in the wp_posts able, but numerous plugins create their own tables, with the ld URL hardcoded.

So I came up with the brilliant idea (i thought) to export the full database, do a text mod of old domain name to new domain name and reimport, but that creates problems because of the requirement that you leave the GUID field alone.

Would the following scenario work – in all cases – ??:
1. Modify wp_options.siteURL and wp_options.home, as well as wp_posts.post_content (leaving wp_posts.guid alone, i.e. on the old, obsolete, URL value)
2. Export to SQL all other tables, modify companydomain.mydomain.com to https://www.companydomain.com and reimport

The problem is, I cannot know beforehand which plugins will be installed, but I do have to offer a fixed price, including the final move, beforehand.
So this needs to be quick, painless and foolproof. I looked at -all- the answers out there, and tested a number of them on some test sites, but most seem complicated and not foolproof, or not future proof, or do not work on plugins.