I'm in a similar situation. My cat is several years old and has spent her entire life indoors, but she recently came to live with me in a house. I started letting her out, only while supervised, and she's come to enjoy it like your kitties do.
At first she was like your cats: she fought me when I tried to take her inside and would bolt underneath the neighbor's gate at the first opportunity. I did a few things consistently and now she's well enough behaved that I sometimes leave her unattended for a few minutes.
Bad behavior means going inside immediately. If she didn't stay in the yard, wouldn't come when I called her, or struggled when I picked her up, we went inside. I'd put her down as soon as we got in, told her she was being naughty, then left her alone. She picked up pretty quickly that even nosing around certain areas (like the neighbor's gate) was not allowed and she stopped doing it.
I give her opportunities to spend as much time as she wants outside. Instead of taking her out when I only have 20 minutes between conference calls, I take her out at the end of the day, grab my phone, and relax outside for as long as she wants. After doing this a few times, she often started to ask to go in after ten minutes. When I do let her outside for a limited time I try to bring her in when she isn't in the middle of stalking or investigating something, which seems to lesson the complaints.
I often call her over to me just to pet her. If coming to you always means something they don't like, why would they do it? I'll even pick her up for a minute to love on her then put her back down to play some more. I do this inside too, so she associates being called over and picked up with good things. She always comes when I call her now, and she rarely struggles when I pick her up. I've even picked her up when was fluffed up and hissing at another cat, and she didn't fight me at all.
When she comes in without a fight, I'll give her a bunch of love and some catnip. She'll usually go to the door when I ask her to now, though sometimes I still have to carry her across the threshold. Make coming inside a different kind of treat and they'll be less opposed. I know she figured out the association, because one time I forgot to give her the catnip and she reminded me quite loudly.
I block off spots I don't want her to get into. It's a good idea to block off access to under your house to prevent rodents and other pests from getting in there anyway. Why tempt them with such a fun place when you can remove the issue altogether? Blocking it off made both of our lives easier.
Hopefully these behaviors will work for you too, and you and your kitties can enjoy the great outdoors together.
Oh yeah... Make sure you treat them for fleas regularly with a safe and effective treatment. You don't necessarily need it if all your pets stay indoors, but you do if they're going outside. And make sure they have all their vaccinations, of course.