I've been mobile for years and have no solution I'm afraid!! I heard you could get a plug for cigarette lighter that would then fit into my dual hive pot but the connections are no use. I spoke to an electrician and when he looked at volts and amps he told me it would blow my lighter. I was prepared to give it a try as I don't smoke so don't need the lighter until I remembered I use it to charge phone. If I'm going straight to waxing client I can pre heat at home but if it's half way through day I just plug it in the second I arrive at client's. I then put up my bed, prepare it, get all my accessories ready and it's usually very nearly ready to go. I use Perron Rigot but I decant from their own pots into the pot I got with wax heater, as it's thinner the wax seems to heat up faster.
Other advice, prepare, prepare and prepare the night before. Never, ever pack a bag and think "oh I must remember to put ?????? in my bag in the morning." You won't remember and will turn up at clients minus wax strips, varnish remover, bed cover, etc, etc! I unpack the minute I get home, no matter how tired or hungry I am then get diary out and pack bags for next day. Start with 1st client and work through your appointments getting each clients kit ready. Obviously if you have 5 manicures it's easy, just check plenty of remover, pads and tools (sterilised as soon as you get in then removed and straight back into nail bag.) and each client's nail files. Personally I assign files to clients and don't mix and match. If you don't have regulars just make sure you brush, spray and mundo well.
Always have too many wax strips.
You'll get very friendly with your mobile clients, something about being in their home I think, but never, ever forget they're still paying customers no matter how many birthday/anniversary/weddings you go to. I did and it's a bit if a nightmare with some clients now!
I carried my single wax pot in a firm hold all type bag, think it's an airline carry on bag and I got it from Watt Brothers. Now I carry my dual pot in a plastic storage box from Asda. In the bag with the pot I had 2 hand towels that I used to put under the pot for protection at clients house, I wedged them down side of pot in the bag. I had 2 tupperwares, one that I used for used strips, spatulas in case a bin wasn't handy. The other I had cotton wool, wee bottle of surgical spirit, tube of sudocrem and my tweezers in (hundreds of tweezers for some reason, think I was ordering in my sleep!!) They rested on bottom of bag and on top of that I had my big towel/s and pre separated towel roll folded (3 of 4 squares per client). I now have plastic sheet and couch roll and no towel to cover bed. Because I had it all wedged in around the pot it never spilled. (Touch wood!) I also never allow anyone to carry my bag or storage box when it has warm wax in it, no one is as careful with heated wax as a beauty therapist who's had to spend a night trying to clean up a spill and ended up have to throw out the pot! ( happened when I first started out and I had the pot in a higher bag, less stable, and placed it on back seat. One emergency stop later it was all tears and snotters!) In pockets either side of bag I have my wax cleaner, strips, pre cleanser, jasmine oil, soothing gel, cotton wool, spatulas and bag that contains my eye lash tint kit.
I'm sitting typing this and looking over at bundle of bags ready for tomorrow. Also one pink shopping trolley that i use for my spray tanning kit. I look like a pack donkey when I leave the house in the morning!
Good luck.