I personally much prefer my packer and STP separate because the dual just isn't comfortable and for the concerns you describe in your questions.
I've tried the nipple/med spoon/ and collapsable funnel. The best out of both for a dual is the funnel because it can fold against your body, but the rest just kinda jab you unless you move it against your body, resulting in an visible boner. I've always had to discretely adjust every time by shoving my hands down my pants, and the best you can do to clean it is point the tubing downwards and shake.
There's obviously problems with these kinds of STPs. The only one I've seen that doesnt have this problem is the peecock. Apparently you can hold the shaft and use to fingers on the same hand to position the funnel. No tubing involved and nothing jabbing against you. You'd still need to be careful about cleaning up after yourself, but I think it's better than the rest. There seems to be a larger learning curve though.
I've heard good things about Mr. Right, but I've also heard it's very large for a packer and very stiff- making for the perfect obscene boner. I don't think I'd convert this kind of packer to an STP, but that's just my 2 cents.
g'luck.