Old technology, dirtybird. Baxter IV bags are thicker & tougher than balloons, baby bottle liners or plastic bags. There are also thick vinyl (?) fuel cells made specifically for our use. I also use them in my gas rc race boats. Slamming & bouncing at 60 - 70+ mph on water with 5 other 4' boats creates a rough ride. We race regardless of the water conditions, whitecaps included. 4 to 5 six lap heats a weekend, maybe 7 races a season, plus 8 to 10 test & tune weekends added to that. One hull races in 2 classes, so double those numbers. Never had a "baggie" break, maybe only seen 2 in 11 years of racing with average 100 boats at any given race, some 250 boats or more. You do not have to access the bag to remove air. Set up properly, fill part way with the inlet up, reverse pump to purge air, when you get solid fuel with no bubbles, switch rotation to finish filling. Bag collapses as fuel is used, no air ever, even with a partial fill. No clunk, inlet fitting is inserted into bag slightly past flush, tie wrapped, done. Only requirement is to have a view of the bag to watch for air being purged & bag being full. On most sport flyers, looking in through a cockpit window should work. On a nice scale plane, a small hatch might be needed for visibility. As most full scale planes have maintainence access hatches, you could make that detail a real access panel. Go to the sites I mentioned earlier & see what's available today. It's not your father's Buick. Trust me, if they weren't durable, I wouldn't be using them in competition where points & my results for weekend were on the line. I travel 200 to 300 miles one way, 2 nights motel bill, 3 days eating out, 6 to 8 times a year, sometimes farther & more days for Nat'l events. Finished 2nd in Open Offshore last year at the IMPBA Gas Nat's in Rochester, Ny, so this ain't my first rodeo. Too much $ invested to rely on unproven (or outdated) technology.