I forgot to specify but what I meant by "gaps" dind't exclude dangerous tarrain - only impassable and such that would cause mishap. Deepstriking and taking dangerous terrain tests is something that should be expected.
Clearly the amount of terrain, of that given type that blocks deepstriking, is what causes the problem. In that regard "How much terrain" is another topic altogether. The club, my gaming group and I visit, has 6 very distinctive tables with terrain, ranging from forests through cities and deserts. We regularly play with more than the 25% table space, taken by terrain, recommended in the rules (the terrain btw is of all variety) and no one has experienced the problems you describe. In addition we constantly switch from per-arranged terrain to the variant in which players arrange it according to their strategy.
I'm sorry to say this, but your problem(if it can be viewed as problem at all - it depends on the point of view) is entirely local and has nothing to do with anything associated with the deepstrike rules/tactics/strategies themselves, which you limit by placing too much terrain. You play this way by choice (whether it is your choice or another one's is another matter).