My first question is: have you organized an event before for an established group of BT players?
This should gauge your expectations. If this is your first go at organizing a BT event with no knowledge of players and their commitment, I'll just be direct, while I love your level of effort, you went way overboard.
Starting out, I would never recommend setting up an event with multi unit forces. Each player should field one mech and be either a free for all or two teams. Let's say 20 people show up, you can have 4 teams of 5, two separate tables.
You need to take notes and sort out player's skill levels, competitiveness, knowledge of the rules, etc.
There should also be no requirements of paint on yourself or others. That's a massive level of effort and cost for an unknown outcome. The entire goal of a first event meetup potentially starting a group is just to meet and do something. Some minis will be painted, some won't. The basic maps in the starter box is more than enough to just play a game. You, as an established player are probably going to have 20 or more minis that you already own to bring that can be used by other players without any additional purchases on your part.
I also recommend using a FB group so that you can set up actual attendance polls so people can confirm yes/no they will go. Trust me, I know that adding a "maybe" option is your worst enemy because you will be waiting until the morning of the event and not see them make a final yes/no selection.
I'd say to really reduce the pressure on yourself. You are not paid, you are a volunteer, while you are taking on the role of a GM, there is an expectation that players have resources (maps/minis) available to contribute in some way to help an event go smoothly.
