So I just need to stop feeling dispondent about 4 or 5 miles on the bike and think of it as a gym work out and sweat my butt off?
Yeah, think of it as a gym workout.
Distance is only really relevant as a goal in itself - eg if you're doing an audax or sportive. If your target is to get fit (perhaps in order to be able to complete a 100 mile sportive or 200km audax), there are much more useful ways to measure your efforts - eg how long you've spent in a particular HR zone. Miles are totally irrelevant as a training metric.
HIIT is one option, and a turbo trainer is particularly good for that kind of thing, but you can also do endurance sessions - as long as you have the willpower to keep going for long periods with just a view of the garage wall to keep you motivated... The point is not to sit on the trainer and just pedal for a certain amount of time until you achieve some notional distance but to structure your workout using power or heart rate (or just perceived effort) to gauge how much work you've done.
I am very tempted to try one of the virtual trainer options but I just don't feel I have the stamina or fitness to make the most of the software currently.
If your fitness improves from using a smart trainer then you
are making the most of it. That's what they're for, just like any other trainer. The only difference is that using a smart trainer with an app like Zwift is supposed to make indoor training more fun, so in theory you will be more motivated to keep up your efforts and therefore more likely to see beneficial results.