You will 'not' want to be against the walls so make room. Listen close to Hotrodpaint and Spraytech,they are speaking from hard earned experience,I can tell. Listen close,if you spray on the grass,look for bugs,AND MOST IMPORTANTLY, if you spray inside plastic,without hvlp gun and/or exhaust air look to incur some health problems. I suggest a fresh air system,especially if you are useing a issocyanate paint. I have done quite a bit of painting in a garage lined with plastic and it will ruin your lungs if you are not useing the proper mask with some exhaust fan. Your more than likely useing a urethane system and you know the dangers of breathing to much of that,well,plastic really makes it bad. Any buggs of course can be touched up. You sound like you are concerned with all the safety and tech. concerns,I'm sure you'll do a good job,just make sure you look at all the safety concerns. Also, plastic will raise the temp.15-20 deg. on a sunny day.