Lost all brake fluid...now what?

TL;DR I literally bleed the brake system dry. What's the best course of action for not doing major damage?

Not my car, it's a friend's. The rear axle literally broke a mile from my house. Limped it hear, he bought a new one from the dealer. I was able to get it installed. All the old parts got reused. One of the bleed screws broke. Got it out and replaced. Now here comes ThatIdiot part. I didn't want to reinstall all the brake hardware as was unsure how the wheel cylinders held up to the torch magic I used getting the bleeders replaced/unseized. So.....I used a couple of clamps to hold the caps in place as I was trying to engage the ECB Invalid Mode. While doing the chicken dance one of the clamps slipped unbeknownst to me. So now the reservoir is bone dry, not sure how much fluid is left in the system at all. I've got a car hauler if needed, but if I top it off with fluid and get it to my mechanic with the fancy shmancy Strap-On Super OBD 220000 will he be able top bleed the system without any major damage?
Would it be okay to drive it there if I disable the regen? I did search but all I could find was DON'T RUN IT DRY! not what to do when you run it dry.
Thank you.

 

Thank you very much for the tips, I was afraid this was going to end up being really expensive.
There were zero rubber caps on the rear bleed screws, doubt they're on the fronts either. When I get him rolling again he will have all the rubber caps in place. As a bonus he'll have a full fluid swap.

I'm calling in a favor with a mech friend of mine, he's going to come by my house with his Strap-on Whatever9000 Mon or Tue evening. I'll be burning up the one favor owed but it'll be worth it.

I'm curious though, I've got a power bleeder setup I've used several times, if I adapted it to the Prius would it be helpful? For those unfamiliar, it's a hand pump sprayer that hooks to the top of the master cylinder reservoir. Pump it up to 3-4 lbs and crack the bleeders one by one in a conventional braking system. I figure putting 1-2 gal of brake fluid through the system should get the air out...we'll see

 

Just wanted to report.
TL;DR: Got her back home safe and sound. I had to borrow a Foxwell NT-630 from an associate and I did the "Changed Actuator" bleeding sequence.

So the driver's side rear wheel cylinder had to be replaced since it blew out when I was doing the chicken dance and drained the reservoir which got me to where I was at the "start". The only place I could find it in stock was at NAPA, but not the warehouse, which was odd. But thank goodness they had two. When I was attempting the "bleeding" procedure the seals in the passenger side wheel cylinder gave out so the Prius owner went to the same Napa again and got the other wheel cylinder. I bought what was supposed to be a Foxwell 644 from a local pawn shop...only to find out it was actually a 614 which doesn't do anything I needed. That was a whole ordeal in and of itself when at first they said "We don't warranty tools" and I replied "I'll see you in civil court" and in the end they did make it somewhat okay. Turns out one of the fellas I work with had the NT-630 and he let me just borrow it.
When I was getting ready to do the bleeding procedure I hooked up my pressure bleeder with 1/2 gal of brake fluid in it. Got everything set up, pressurized it, turned my back and the rubber cap slipped off the reservoir and 1/2 gal of brake fluid ran down the firewall...well this is turning out fantastically. I did my best to flush everything with soapy water and then I got a gal of brake fluid dumped the entire thing in the bleeder, made sure the clamp on the PVC DWV flexible cap was at the bottom of the cap, against the "lid" of the reservoir. I made sure the smart key was no where near the car and I removed the ABS motor fuse, and flushed a quart or so through the front calipers. I pressurized the system again and plugged in the NT-630 and went through the Bleed ABS "changed actuator" sequence. As I following the prompts I kept the bleeder up to 10 psi when it would get low. I used the pressure bleeder to act as insurance the reservoir wouldn't get low. Even during the accumulator pressure fluctuations it didn't seem to bother anything. Granted I was rather nervous something would blow or go wrong but so far so good.
After it was all done, scanned the system and no codes. I took the car for a little spin, did some emergency brake checks up to 50 mph without issue. I then found a gravel road and attempted a few full skids. The ABS system was going nuts but no tires seemed to lock up. Unfortunately I couldn't find the Stroke Simulator bleed screw (the one on the master cylinder) which is not ideal but it's the situation...did the pressure bleeder encourage any air pockets to move out at the wheels? I hope so.
Thank you all for your help and your advice.