Is Anagarika procedure a necessity in Thai Forest Tradition?

That whole point of ordaining isn't just to leave home, it's to leave your very self behind. Monastic ordination in any tradition - Buddhism of any stripe and otherwise - has a component of complete obedience to both the precepts, the rule, and the community. If that the way it's done, that's the way you do it. Your anxieties, reservations, or oppositions simply aren't important.

Master Dogen writes that to study the way is to study the self. To study the self is to forget the self. To forget the self is to become one with the 10,000 things. So many modern people are pretty keen on studying the self and becoming one with the 10,000 things. Forgetting the self, though, that's hard. But it's the lynch pin that everything else depends on.

Good householder,

As for the Noble tradition, the Sublime Buddhas Sangha, such as Anagarika (a householder without house...) is unknown and seemingly a merely new, Sri Lank originated custom. Yet there are communities with agree on what is called "Sangha-agreement", of which is only allwoed if not against the Dhamna-Vinaya. Generally the Sublime Buddha wished to let people fastly ordain, since faith, good mind states, are all but not sure and doubt the greatest hindrance. So he also rebuked communities agreeing on similar things. There are clear rules set out by the Teacher and also clear restrictions, yet, if ordaining or not, is of course not up to any right but compassion. So nothing that should be claimed at first place. Not giving, or demand certain things, may have reasons, sometimes right, sometimes wrong judged.

The only, of which comes near such prove time, is the decleared prove time for wanderers of other sects (as for higher ordination, not explicit for going forth), whether they are really fit and earnest toward the Tripple Gems or not. Sure, most modern, westerns, would fall under this category, yet different in each individual case, of course.

There is, how ever, no real indication that such a test phase should be spend as householder. And formal, if one asks for leaving house under the Gems, taking on 10 precepts, one becomes a recluse, pabbajito, and not sure if giving such without giving robes, check if the requester has sufficent, wouldn't be actually an ordainers fault.

In all cases good if always seeking out communities with less doubt that this Dhamma-Vinaya has been layed out good. This includes of course to tend oneself to it as well, starting by being aware of being a receiver of compassion, either for the sake and bond toward the Unbound or toward the world and it's common communities.

Don't wait anyway, what ever hard ship might be feared, times is running out and skillful mind and good intentions, possibilities, even faster, good householder.

Firstly, I feel one should avoid having a romanticized view of either the lay married life or the celibate monastic life.

Being a married person, you may find that your spouse, children and in-laws may often not be in line with your wishes and expectations, and may be a source of grief.

If you read the book "The Broken Buddha" by Ven. S. Dhammika, you will find that many monastic communities today are not living up to the standards of the Buddha's Sangha, to put it mildly. Also, please see this answer. A zealous person joining the monastic order today may get disillusioned by this.

Hence, it makes a lot of sense, to become an anagarika first, and then a novice monk (samanera) next, to try out the monastic life for a short time, as a trial, by staying in a monastery under the guidance of a teacher. In the end, you may find that this does not suit you, or the other way round. It's a practical way to guide one's decision-making.