So if you file 1b (intent) that is fine but then you have to pay a fee and do another filing (iirc $100 more) when you finally use the trademark. And wait for approval. So if you can start to use it (in the class you have filed in) right away that is the cheaper route. Generally this is stuff that lawyers have little benefit in telling you since they get extra money for doing the extra work for you. And of course it is probably more ritualistically or legally correct. But if you are going to be lean you will have to cut corners and take some nominal chances. Important point.

Or operate the site that they see at something like

joeblow.mydomain.com instead of "www.mydomain.com". And give them that address.

Or simply give them screen shots actually even easier and say it's pw protected and only open to selected users.

There is stuff to know, not a big deal, but hard to summarize in a HN reply.

We got a trademark by putting up a site which literally was created by putting a logo on a customink.com shirt, screen grabbing, submit that to the trademark office and say that was the product. This is not a patent. It's a trademark for a logo or for words, right? All you have to do is show you are using it. In general.