Yeah. You have basically two choices with crawl spaces ... free range or walled city. I went to walled city... it worked very well once the fauna population was managed
I live in a single wide mobile home and other than some spider webs under the house I haven't had any problems with critters getting under there.
Last winter My 50 feet of sewer line froze up solid and had no choice but cut it up in 5 foot sections and replace it at -20*f
I keep it insulated now.