Re: What Army are you working on and where are you getting minis
I'm a little reluctant to just skip the tunnel rules altogether, since it's (for me, at least) a big chunk of the Bug's flavor. Might be able to simulate a lot of it with the Covert Ops rules, though...
That would be the best bet as sneaking in particular has several similarities with tunneling movement (such as conferring a degree of ablative cover). It's not nearly as surefire tho since sneaking troops can be spotted and then attacked normally, which of course isn't the case with SST tunneling troops. But then again, a lot of the things won't be the same anyway so I'm not sure if it matters all that much.
The SST bug list indeed isn't all that massive or complicated. In fact I think Demian's "archetypal" bug army list (the Organic/Biotech one that is) would be able to cover a big part of it (despite the fact that SST bugs are all at least SZ 3).