Choosing Udon Thani as a central hub is a firly good idea since UT has 2 areas with bars including a few mixed bars. You could have choosen Khon Kaen too. Whatever you do in Issan, you might have the feeling you're not in the right place for action, so you'd better move to another place. Instead of butterflying as you might have done in Pattaya, BKK or Phuket, you need to jump on the opportunity when you find one.
I suggest you read a few posts in my TR, especially this post. Ladyboys I met in Issan are Apitchada, Run, Beer, Teeratcha, Pam and Mikki.
I don't know if the idea to find a hup is the best one. Once you've visited a city, it's probably better to move to another one unless you have a heavy stuff to carry with you. If so, instead of looking for hotels, you could look for an appartment in airb&b.
Choosing Udon Thani is questinable since UT is fairly in a remote area. Maybe Nakhon Ratchasima could be a better option.
Here are a few points I remember :
*) traveling by train had been a good idea. I went to Nong Khai in one night in a first class coach train for les than 1,000 bath.
*) Nong Khai : I found nothing in this town. It's really a small countryside town. If I had had more time, I would have pushed to Vientiane since I could locate ladyboys in Vientiane using my Wechat.
*) Udon Thani : I found bars and ladyboys over there. I actually used Wechat and Thaifriendly App and hooked up a ladyboy working in a bar and a ladyboy wanking with her friends. The bar ladyboy was cheaper than in Phuket or Pattaya, but she attracted me to her bar to get LDs. The other ladyboy was not really adapted to going with a farang.
*) Khon Kaen : I tried to search the bar area around the Pullman hotel to see ladyboys and haven't found one. I must reckoned I had been busy. On my first evening there, A ladyboy coming back from work found me (Pam) and spent 2 nights with me. I can tell you that this type of girlfriendly meeting is completely different from barfining in Pattaya.
*) Ubon : I hadn't planned to go to Ubon Ratchathani, but buses to go to Si Sa Ket were full. I hooked up a student using Wechat. She could have been better. If I had wanted to stay in Ubon, I would have found an hotel closer to the university
*) Si Sa Ket is a shithole with a fruit & vegetable market and a fish market. This is what the downtown looks like. I first got bored since I had to meet a ladyboy hooked up in Thaifriendly. She was looking for a sponsor to open her hair salon but wouldn't give even a kiss in return. I then hooked up a ladyboy using Thaifriendly App. She had worked in Phuket and I had one of my best times with a Thai ladyboy. She never returned to Phuket then.
*) Buriram is a shithole too with a few empty night bars. I had a contact with a ladyboy but she never showed up. Some people pretend there are ladyboys in Buriram when reading profiles in Thaifriendly, but what counts are the ones who answer your requests when you are there. result : none.
*) Nakhon Ratchasima : I stayed less than 2 hours for a transit. Maybe I should have stayed there to explore.
*) Ayutthaya : interesting cultural visit but no ladyboy. Issan can be defined as the place where Siem and khmer civilisations mixed during the middle ages. Siems were beaten in Siem reap and Khmers were stopped in Ayutthaya. The country between both and around is the country where ladyboys live.
*) Chaiyaphum : I should have gone back there in 2017. This is a small city too but a few "stars" of Pattaya came from this city. If you have time and if you do want to explore small cities looking for a ladyboy fresh from the farm, this is the place to explore.
Don't forget to upload teh following apps in your smartphone : Google translate, Wechat and Thaifriendly.