I have recurring balance problems and was going to sell all my bikes including my 2 wheel lwb recumbent. Some days ago I was looking around on Amazon and found training wheels' bike stabilizers' for adults. I should get them next week. I'm going to start out on my trusty old beach bike, but it may be that such accessories may blow a breath of fresh air into 2 wheel lwb bike sales or for that matter any 2 wheel recumbent.
As far as test riding, no one gets to ride my personal bikes. And of course there is the now famous story of the guy who test rode a $5,000 bike at a shop and didn't come back.