In my experience with 15+ years of MCA National events, these are pretty decent rates. Taxes will be added so that is a given. As I recall, the rates for the 40th were about the same you are seeing from this place. I would recommend blocking for everyone signed up plus a few more. Get the blocking code for the group and everyone makes their own reservation on their own credit cards; any rooms left after 30 days of the initial blocking date can be released back to the general public. Let's face it, by the end of the year, 90% of anything within reasonable distance of the event will be sold out.
The way gas prices are rising, a hotel room may be the least of expenses for any of us traveling 700+ miles...
BTW: that location looks ideal !!