You can stay in or out of Thailand. I have this visa, dead simple and as long as you paid outside of Thailand by a non Thai company this is OK. Worth using a knowledgeable agent on LTR as minor things can trip you up and they spot them in advance . I used
I did same for 2.5 years.....in and out by air every weekend . Never an issue, asked why once and said my girlfriend is here. If you don't break law overstay etc you will be fine