Sounds to me like you have the "Best" mattress for your situation. Of course you could try one of those air mattresses used on the couch w/the fold out bed in the front part of your MH. Anyway, No air chamber is 100% air tight, especially if you put weight on it. You will have to "fill'er back up" every so often. I mean you see how balloons deflate after 4-6 days after you tie them off, no matter how tight you pulled/tied that knot. Also when storing the rig/mattress for longer periods I would want the mattress to be in a deflated state anyway.
I have the same mattress and I had my share of problems with it. But as long as the air chamber and the valve on the air chamber is ok you should be able to get away w/an easy fix. Mine kept deflating because the Irresponsible and inattentive tech placed the (steel reinforced) hose across the Rail (where the bed slides up and down on or from the normal position to the Stored position), instead of underneath it thus causing the hose to be severed or truncated. Also, the tugging of the hose, caused by the hose being pushed back and forth by the bed along the rail, caused the Cam Lock inflator-connector to crack/break off (the extremity that inserts into the hose). The Cam Lock inflator-connector connects the hose to the "Inflator" (air pump). Basically we inflated the mattress, lifted the bed, listened very closely and heard a little hissing, so we followed the hose from the valve at the top of the air chamber to the air pump and found the perforated hose and the broken off Cam Lock inflator-connector. So I called Innomax and ordered 3 Cam Lock inflator-connectors (2 spares) they were only $9.50 a piece. If you want you can also get the steel reinforced 1/2 inch hose (8 feet) but it's expensive. A 1/2 inch diameter air hose or water hose from Wal-mart will do (once you get home just cut the necessary amt of hose that you need). So unless the mattress is uncomfortable or hurts your back, I wouldn't give up on it. JMHO