Yes, you can absolutely be a solo guy and date any one poly woman, or a mono woman, if she's fine with being mono while you're poly. And you just establish the understanding that you both can continue to date others if you wish. So, you're in a relationship, but you're still on the market, so to speak, until you find another good person who qualifies as a partner (could be more, but many people are at their emotional and time limit with 2 partners, unless there are long distance, infrequently seen partners in the mix).
My gf's bf (my metamour) is (in practice) mono. They've been together about 8 years and he's fine with just having her spend about every weekend with him, or more time if she's available. He's rather introverted and wouldn't have the bandwidth to carry on two relationships at once. He's "allowed" to date others if he wants, but he just doesn't want to.
I've also had bfs who didn't date any others while we were in relationships.
So, for both me and my gf pixi, we each have a gf and a bf. But her bf Malachi is not romantically involved me, and my bf Aries is not involved with pixi This is called a V. I am the hinge of a V, with pixi as one leg and Aries as the other leg. And likewise, pixi is the hinge of her own V, with me as one leg and Malachi as the other leg.
The four of us don't often hang out as a group except for the occasional holiday dinner or a night of D&D. Generally I spend the week with pixi, and on the weekends she goes to her bf's house and my bf then comes to this house.
My bf Aries is poly. He's been open to other relationships since we met. He has been on a few dates. Nothing has worked out yet, even though he's gone on a few first and second dates. Maybe the newest person, with whom he's been on 2 weekend long dates, will work out. But she's quite busy and he said she's only going to be available maybe once a month. I think she has 2 other bfs. (Or maybe she'd call them play partners; I don't know.)
In working polyamory, Vs are much much much more common than triads (where each person is involved with both other people).
Opening Up is geared to couples in some ways, but don't be deceived. There are working poly principles in it that apply to everyone, things about time sharing, jealousy/envy/loneliness, money management, long distance relationships, NRE, communication skills, who meets where (hosting), what about kids?, hygiene (changing sheets and whatnot), discretion (not sharing TMI between partners), dating woes and issues, breakups. It also addresses the differences between polyamory and swinging.
I am not sure how basic poly principles can become suddenly outdated after a few years. I will take a look at the Amazon reviews and see what is meant by that. I think Ethical Slut made out poly to be all about large kinky sex orgies, which it certainly is not (usually).
My gf and I started our relationship as open/poly. So we didn't have to try and change a long term mono relationship to a poly one. That is difficult. Many people try to do that, since mono is the norm, but poly is becoming more popular and people are seeing it's more ethical than cheating and more convenient than serial monogamy (and divorce/remarrying).
Polyamory is popular among young people, but they often fuck it up, because at that age you don't know yourself well. You can barely communicate and negotiate with one partner and manage to get along, much less juggle 2 or more relationships at once. Polyamory is not superior to monogamy, but it is harder to do just because there are more moving pieces. It's more like chess, and monogamy is more like checkers.