I suffered a bit of nerve damage in my upper thighs many years ago from skiing with under-insulated legs on a minus 35 F day. As a result, I ended up trying a lot of bottom layers for extra protection. My favorite under-shell layer has turned out to be a pair of fleece pants I bought from REI 15 years ago. They are a substantial 200 weight Polartec, and they fit close, but not skin tight. I'm tall, but I bought a regular length so there is less bunching when I push them up above my ski boots. On average cold days, I wear them over skin-tight Helly Hansen Lifa. On very cold days, I layer them over Patagonia power stretch tights. Never have any problem with them clumping.
These exact fleece pants aren't made anymore, but REI does have a model called Muir Woods Fleece which look like a similar fit (maybe a shade looser), but may be a little lighter weight. That's probably a good thing for normal legs. They come in three inseam lengths, and have ankle zippers (which miine don't). They list for $69.50, but will probably go on sale later in the season. Maybe they would work for you.