I wasn't going to chip in @SoMentallyDrained because I don't have a spaniel and our dogs have all slept in the kitchen. We don't crate but we restrict to downstairs only because of their size.
But I will give my thoughts on neutering. Though, I'm an outlier as always 🙄
We've had 4 intact males.
With a bitch there are some benefits with regard to hormones, risk of pyometra and there are some theories about likelihood of mammary tumours also. With a male there is less to be gained from neutering and more potential negatives.
You mention changes to the coat, there is also the weight issue post neutering, potential for increased anxiety and male neuters becoming reactive/defensive towards other dogs. With a giant dog we were not willing to risk that so we opted not to neuter.
We never had issues with other dogs attacking them once they were adolescent/adult, no humping problems, no scent marking indoors even when a visiting dog (sister-in-laws collie cross) peed all over our kitchen 😡
At the moment we're considering a male as a companion for Brie. My cousin's daughter is a vet and when I asked her advice about whether to neuter boy or girl she said definitely girl, but not until she has turned two years, s liely late summer next year but only if we get a male pup.
With regard to the toileting, a full wee is a different matter from scent marking/territorial behaviour anyway, so it's not really relative to the neutering thing. Our first bitch was unreliable with wees for much of her life and I know it's a bit of a nightmare to deal with. As others have said, it may be a case of going back to basics and hoping that you can train it out of him to some extent.
Good luck anyway x