At least you have an electrician on hand to do it for you. I'm not up on code so you may need to have your electrician check up on it. The cheapest I might go would be a set of tails with Cam-lock connectors that has it's own fuses or breakers that match the maximum power you expect to be drawing, then plug your racks or distro into that. Most of the large equipment you might rent will come with Cam-lock connectors. The best way isn't to use tails, but to have a separate panel with surface mount Cam-lock connectors that are set up in such a way that all of the covers are mechanically linked. You have to connect the ground first, then the common can be connected followed by the hot leads. Code may require it to be that way these days.  Of course that will be many times the cost of just putting in a set of tails. The contacts on the Cam-lock connectors are recessed so you have to make an effort to zap yourself or short them out, but you can put fingers or other things into the holes. For that reason, you should probably make sure the tails can be in a locked up when not in use if you do try to get by with the tails.

Thanks for the replies. Sorry, I thought I put a link to the panel we are looking at: