I always understood that it was only you that had the power to decide to host these models on your site. Bugs aside, I don't think you would need to account for much permission; Bdaneal's license for his newer stuff allows you to freely modify the models and redistribute for free on line. Still, it's all up to you on the fate of the P2. I can't control your decisions, instead influence, inspire, and /or encourage.
I'm confident, that you yourself won't regret the possibility of you uploading the P2 on your site when you're finally happy and satisfied with the work you've done to make it possible. Ever since you first asked for help with the cylinder exhaust bug on the P2, I've supported and respected your interests. Reviewing Bdaneal's license, there is nothing stopping you from uploading the P2 permission wise.
I am also a reskinner that publishes work I'm happy with, as long it the license says the original asset is open-source. I never regretted uploading my work to the DLS that is based on free material, and people highly appreciated what I contributed. I have a few caboose reskins on the DLS, and downloaders were happy to use my content on their routes and sessions. I'm thankful for the constructive feedback they give, and makes me feel proud.4
You've also mentioned that you haven't found any other bugs that would prevent the P2 from running normally or ruin the experience, so that's another plus.
You based your P2 on work that is open-source; it can freely be modified and uploaded without asking for permission first, but anyway, it is always to credit the original authors. Making sure that the model is polished is also important, and I can see that you worked hard to make sure that running the P2 is a smooth experience, as best as it can be. Just ask yourself what other things you should consider when in the case you elect to upload it; documentation, hosting the file, publicity, etc. Take this advice into mind and maybe you can make something good out of your hard work that you invested much time, effort and other resources that will make your projects into a smooth and finely polished experience you and everyone else who potentially installs it on their copy of Trainz can enjoy free of the worries and stress of errors and bugs that come up running the model.
Still, it's all up to you. At the very least I'm happy to help.