Nope, sorry. While I'm pretty sure have some photos somewhere that include our onsite printing setup in the background, I really don't know where to begin looking for them and you wouldn't be able to see anything of much use. When I'm at events I'm pretty busy shooting other things, usually not our booth setup unless it happens to find it's way into the background.
I collaborate with another photographer on larger events, when it's a big enough event we will offer onsite printing. Her husband often helps with that printing, but on occasion we've hired others to help too.
We simply use one of those 10x10 popup tents when we aren't able to set up under cover of something else.
If you get one of these tents, I'd suggest it be a white, grey or black one, since any color will tint the screen of your computer as you try to print, as well as the prints themselves. Out tent is green, and I hate it. That makes getting a neutral print pretty tricky. Wasn't my choice, though, so I just live with it.
Our tent has "walls" that we can attach or not, optionally. These are mesh to keep out bugs, but allow in plenty of fresh air. The primary reason we use them is to control traffic flow and direct customers to one side of the tent. It also gives a small measure of security to our camera equipment inside, when zipped closed. Not that someone serious about it couldn't steal something if they tried hard enough. So, we try to keep a close eye on things and stash equipment inside bins that slide under the tables, out of sight, when it's not in use.
Also get a large banner printed with the words "Event Photography" or something like that. Hang it on the awning of the tent or front of the table. Weight it or tie it down to keep it from flapping in the wind. I had an 18" tall, 5 foot long banner printed by Staples for $60.
We use three or four folding tables and have a couple chairs for ourselves and more out front for customers to sit down while reviewing photos.
You'll need all the usual stuff to be organized: pens & pencils, forms, maybe a few portable drawers to store things in (printing paper, inks, etc.), some of those large plastic containers to pack stuff up and move it, extension cords, staplers, receipt book calculator, etc., etc. Heck, it's your mobile office.
We have table cloths to help hide all the stuff we are storing under the tables. Go to the hardware store and get a bunch of clamps to keep them secure from the breeze, if you use table cloths.
We bring coolers, since at some events there are no food and drink. Even the ones with a food vendor, several times they've run out before we got a chance to take a break.
Often out in 70 to 100 degrees F all day long shooting, we have plenty of liquids, sunscreen, hats and long-sleeve shirts or light jackets handy.
I have a number of sample images, too, matted and in frames. These show sizes for people to compare (just 4x6, 5x7 and 8x10, since those are the only sizes we offer on site) and include special items we offer like photo montages. Displaying 4x6 samples alongside 5x7 and 8x10 samples really helps you upsell to the larger sizes! Our pricing is also framed and on display this way.
Smaller size frames should have a built in easel to stand up on a table top. Larger framed images can be leaned against something. Try to keep anything framed out of direct sunshine, as it can cause fading and/or condensation. Try to choose plastic or light metal frames and acrylic instead of glass, if you do this.
Plenty of business cards with our website URL, and a brochure of service, another with online sizes, products and prices (there's far, far more to choose from online, and it's even a little cheaper).
Overall, just plan to deal with wind and sun, and perhaps - but hopefully not - rain.
We currently work with one portable computer, printed thumbnail catalogs and an inkjet printer. If we did more onsite sales, I'd like to upgrade to a dye sub printer and viewing screens running off a networked server, to make the whole process a little smoother, a lot faster and more cost efficient. (In fact we've picked up some used computers and monitors with this in mind). But, there's a lot of cost to doing this. So, we make do for now and really don't print onsite a lot of the time.
Heck, I've thought there might even be a viable business in building up an event trailer and leasing it and my printing services out to other event photographers, when not busy with my own events. Perhaps it could be based on a flat per-print fee (built into the price charged the print buyers), and perhaps something to cover the cost of DVDs burned with the images after the fact, or travel time/expense. Might even lead to hosting galleries online, etc. I dunno. Might work. Still thinkin' about it. Hey, if I do, and it works well enough, maybe I'll franchise the idea!