BothHands wrote:and I don't know of any way to give them access to my localhost environment.
Nothing easier than that. The solution is the "Chrome Remote Desktop", all you need is a Chrome Browser installation and also the Chrome Browser Extension "Chrome Remote Desktop". Also the Wordpress team (or whom ever you want to grant access to your PC) needs the Chrome Browser and this extension.
Follow the steps for giving access to your Desktop (i.e. you finally have to transmit a certain ID to the WordPress team, that ID is generated by that Extension and they have to enter it in Chrome Remote Desktop), there is no hassle wih firewall or routers, all data is "tunneled" via HTTP Port 80. Really easy to use, free and perfectly fits your needs.
A final note on WordPress and "weird" problems: I formerly had my homepage designed with WordPress, all running fine, but as in your case, things started to behave strange, i.e. finally the site could not be accessed anymore, always a blank page showed up. I upgraded and re-installed everything and everything was fine again. But it did not last very long, the same problems appeared again...
As i am a professional IT, i started an investigation about the problems, same thing as in your case, neither the WordPress team nor my Provider could help, they couldnt reproduce the problem. It did not take very long and i found the reason: my WordPress installation has been hacked, it has been infected by a server trojan! I went deeper into the problems, as again neither WordPress nor the Provider could help, they blamed me(!) for not securing the server (i had no idea, how to do so). I finally found out, that of course my server was NOT the problem, the problem is (and this a horrendously severe problem, which finally caused me to drop(!) WordPress FOREVER(!), i wont use it anymore) the Plugins! Plugins are NOT developed by the WordPress team, Plugins are developed by "any user" in the Word, you simply may send your code to WordPress and they will integrate it (if it is a good one). And there is no security check (what in fact would be very difficult) and if there is an asshole, which simply applies some "bad code" into the PHP Plugins, it simply will be integrated and deployed world wide! And thats what happened to my installation, it got an trojan twice in a couple of weeks, which was imported by any of my Plugins.
If you can give me a listing of all files in your WordPress Base folder and also a listing of your plugins folder, i eventually can tell you, if your WordPress installation is infected. I do not remember the file names of the critical files, but when i see these, i will remember. Anyway, i dont use WordPress anymore, i dont use any CMS anymore, i do not make suicide and I cannot believe, how weak these products are running. I am pretty sure that there are millions(!) of infected WordPress installations, but it does not always lead to "weird" behaviour (that is unwanted by the hacker, of course he does not want that you can find out, that you have been hacked).