Regarding Roger's suggestion, as i'm sure Roger's aware, benching is going to be tough after a squatting etc. How much energy are you gonna have left? Not as much as you would have in any case. And that's before you've hung some weight round your waist, staring down at those parallel bars.
How about doing a three day split, but STILL going to the gym twice a week? This will obviously leave a longer period between exercising the same bodypart, but if you use big compounds they'll be some crossover nevertheless. At least some bodyparts wont suffer because they're always being worked when you're half fatigued?
Do one of the 'big three' in each session (bench, squat, deadlift) and if you feel it's been too long between benching (for example), then couldn't you just chuck some plates in a racksack and perform pressups at home or something?